Tankless water heaters are a whole lot different than traditional storage or tank type water heaters.
They are often considered green because they don’t have the standby heat losses associated with tank type water heaters and are therefore more energy efficient. More about energy and water conservation as related to tankless water heaters later.
Tank type Water Heaters
Tank type water heaters are simple to install, operate, and repair. They are reliable and often the first thing to fail is the tank which begins to leak. In my experience most storage water heaters never need flushing or any other maintenance. Some manufacturers recommend flushing periodically, but I know very few people who have ever performed any maintenance on their water heater. I know people who aren’t even sure where it is. Comparison of water heater types - Water Heater Guide
Tank type, or storage, water heaters simply turn on when the temperature drops below a set point and turn off when the upper set point is reached. It’s the same for gas water heaters as electric. Gas water heaters have a thermostat near the bottom of the tank built into the gas valve, and electric water heaters have two thermostats, a lower and an upper thermostat, which are easy to replace.
With tank type water heaters you set the temperature, or more likely just leave it at the factory setting, and you forget about it.
Whatever the temperature is of the incoming cold water, the water heater still ends up at the cut-off temperature of the water heater. Colder water just takes longer to heat up.
Tankless Water Heaters
Tankless water heaters are sophisticated complex pieces of equipment bearing little resemblance to a traditional storage type water heater.
There are several problems that must be overcome when designing a water heater. In order to heat water rapidly a very large amount of heat must be transferred to the water quickly. A heat exchanger is used for that.
One problem is that any fluctuation in the flow rate will cause a corresponding change in outlet temperature unless the heat source is modulated. Without having a pre-set regulated outlet temperature you would never know how hot the water coming of the outlet would be, it would depend on the water flow rate.
The same holds true for inlet temperature. The outlet temperature would depend on the inlet temperature, so if the inlet temperature dropped 5 degrees so would the outlet temperature. In most areas it would be substantially different in summer than winter.
Another problem is protecting the heat exchanger. If the flow of water is too small, it won’t cool the heat exchanger enough and the heat exchanger could become damaged. The heater could become a steam generator.
In order to obtain good temperature regulation and protect the heat exchanger tankless water heaters use sensors to detect things like the inlet water temperature, outlet temperature, water flow rate, gas flow rate, gas pressure, and flue temperature. It’s very complex. Some tankless heaters regulate not only the energy input, gas or electricity, but also regulate the water flow.
Gas tankless water heaters also need a large gas line to supply all those btu’s and a large venting system for all that exhaust.
One of the problems with high efficiency is that the highly corrosive exhaust gasses condense on the walls of the venting and can damage the venting, the heat exchanger, and other parts if it is
If you have a dishwasher make sure that it draws water at a high enough flow rate to turn on the tankless heater. Many do not. Washing dishes in cold water is not very effective.
Here are some links to a comparison between several brands of tankless water heaters and some other tankless water heater articles. Compare Tankless Water Heaters, Bosch, Rinnai, Takagi, and Noritz.
Tankless Water Heater Maintenance
Scale must not be allowed to build up in tankless water heaters as it can restrict the flow of water through the heat exchanger. Generally the warranty of a tankless water heater will contain a figure for water hardness that should not be exceeded. If your water is too hard it will void the warranty. They recommend a water softener ahead of the heater in those cases.
Remote Controls
Many tankless water heaters have remote controllers. Tankless heaters only work within a certain range of output temperatures. If your temperature is set too high or too low for a specific task or flow rate, then you need to adjust the output temperature for that use. There is usually a control panel on the water heater, but it can be inconvenient to run out to the garage when you are about to shower and notice the temperature is set wrong.
Tankless manufacturers therefore offer remote control units so you can adjust the outlet temperature to meet your specific requirements for whatever you are going to use it for.
Electric Tankless Water Heaters
Electric tankless hot water heaters are not very popular do to the amount of electricity they require. For a whole house type application you typically need to run extra heavy electrical wiring and have a separate set of breakers for the water heater. Often you will need an upgrade from the utility company to get that much electricity to your house from the grid.
Water Conservation with a Tankless Water Heater
Cold water must pass through the heat exchanger to reach full temperature. The water in the heat exchanger when the heater comes on is cold. It takes time for the water to flow all the way through the exchanger to the outlet to become fully heated.
It therefore takes longer for the hot water to reach the fixtures. Longer waits for hot water means more water running down the drain, which leads to more wastage of water, not water conservation.
The Australian government did a study of a number of brands and models of tankless water heaters and found that on average a tankless water heater to from 10 to 20 seconds longer to supply water to the fixtures.
Tankless Water Heater Installation
Installing a tankless water heater is not something for the amateur. You should have a factory certified technician install your tankless heater. Poor installation is the number one cause of problems associated with tankless water heaters. A poorly installed tankless water heater can wait years before acting up. More about tankless water heater installation.
Venting is critical in gas heaters, as is gas line sizing, water flow, combustion air, and condensate drainage if needed is also very important. Freeze protection also becomes an issue with tankless heaters. The warranty won’t cover a heat exchanger damaged by freezing.
Sizing is another critical issue. Too small or too large a heater for your application will cause you problems.
Common Tankless Water Heater Problems All the common problems assoicated with tankless water heaters.
Wednesday, July 28, 2010
Sunday, July 25, 2010
Tankless Water Heaters Waste Water!
Tankless Water Heaters Waste Water Compared To Storage Heaters
As is well advertised, tankless water heaters save energy. Tankless water heaters do not have a tank full of water slowly leaking out heat energy 24 hours a day. Gas tankless water heaters usually don’t have standing pilot lights.
Endless hot water
One of the benefits, possibly the biggest benefit, is endless hot water. There are pros and cons to endless hot water. Some family members may end up taking much longer showers for instance, causing you to spend more on heating water than you would with a storage heater.
Tankless water heaters do not conserve water
With a tankless unit, there is no hot water ready and waiting to flow off to the tap. The water in the heat exchanger is cold. So first the water must be heated by passing through the heat exchanger, and then make it to the tap. It takes longer to get hot water to the fixture.
This means you are running more water down the drain while you are waiting for the hot water to reach the fixture, and finally stabilize at the desired temperature. Here is more information about tankless water heaters and wasting water. Tankless Water Heaters Test Results
A hot water demand system solves the problem
There is a fix; a hot water demand system would solve the wasted water problem. With a hot water demand system you won’t run any water down the drain, and you don’t wait as long either.
A traditional full time hot water circulating system with a return line from the last fixture back to the water heater will not work with most tankless water heaters and will probably void the tankless water heater’s warranty. It would either keep the heater on all the time, or it wouldn’t pump enough water to turn the heater on at all, depending upon the size of the pump.
By combining a tankless water heater with a demand type hot water circulating system you get the best of both worlds. You save energy and you save water. Perhaps best of all you save time since you don’t have to wait as long for your hot water.
As is well advertised, tankless water heaters save energy. Tankless water heaters do not have a tank full of water slowly leaking out heat energy 24 hours a day. Gas tankless water heaters usually don’t have standing pilot lights.
Endless hot water
One of the benefits, possibly the biggest benefit, is endless hot water. There are pros and cons to endless hot water. Some family members may end up taking much longer showers for instance, causing you to spend more on heating water than you would with a storage heater.
Tankless water heaters do not conserve water
With a tankless unit, there is no hot water ready and waiting to flow off to the tap. The water in the heat exchanger is cold. So first the water must be heated by passing through the heat exchanger, and then make it to the tap. It takes longer to get hot water to the fixture.
This means you are running more water down the drain while you are waiting for the hot water to reach the fixture, and finally stabilize at the desired temperature. Here is more information about tankless water heaters and wasting water. Tankless Water Heaters Test Results
A hot water demand system solves the problem
There is a fix; a hot water demand system would solve the wasted water problem. With a hot water demand system you won’t run any water down the drain, and you don’t wait as long either.
A traditional full time hot water circulating system with a return line from the last fixture back to the water heater will not work with most tankless water heaters and will probably void the tankless water heater’s warranty. It would either keep the heater on all the time, or it wouldn’t pump enough water to turn the heater on at all, depending upon the size of the pump.
By combining a tankless water heater with a demand type hot water circulating system you get the best of both worlds. You save energy and you save water. Perhaps best of all you save time since you don’t have to wait as long for your hot water.
Friday, July 23, 2010
Instant Hot Water – What Are The Benefits and Is It Really Green?
Instant hot water must be defined. I see advertisements for instant hot water in ads for tankless water heaters, hot and warm water recirc and circulating systems, hot water demand systems, and point of use water heaters.
Truly instant hot water would be for instance if you have a traditional full time hot water circulating system with the proper plumbing layout. You would have hot water immediately upon opening an hot water fixture or faucet, that being within 2 or 3 seconds anyway.
Obviously for convenience this would be the best scenario. However there is a high price to pay for such a system. By continuously circulating hot water through your hot water plumbing you are wasting a huge amount of energy. Using energy costs money and contributes to greenhouse gas emissions.
There are also circulating systems that utilize the cold water piping as a return line for the hot water circulating system. These systems which include the Laing, Grundfos, RedyTemp, Watts, and others, are what I call “warm water circulating systems”. These are temperature controlled recirc pumps that typically turn on the pump when the water temperature drops to 85 degrees, and then shuts off when the temperature reaches 95 degrees.
Like the hot water circulating systems these systems keep warmer than normal water in the piping causing an increase in energy usage and corresponding green house gas emissions. However, the water isn’t really hot, it’s warm to cool. Your body temperature is 98 degrees so the water might not even feel warm, perhaps “cool”. Anyway, you still have to run water down the drain to get “hot” water and you are wasting energy too. I would have a hard time calling these systems “green”.
Another method is to use a point of use water heater where the heater is located so close to the fixture that there is virtually no wait for the hot water. This is a green type of plumbing system. You don’t waste water running it down the drain waiting for hot water to arrive, and you don’t circulate hot water and waste all that energy.
However, point of use water heaters are not very useful in most residential settings. For one thing you would probably need more than one water heater, and that can be expensive.
Not much else you can do to have instant hot water. And even point of use water heaters don’t always get you instant hot water. For instance, if your point of use water heater is a tankless model then you once again will not have instant hot water. A tankless water heater typically requires the water to flow all the way through the heat exchanger to reach full temperature. This means that you have to purge water out of both the hot water piping and the water heater’s heat exchanger before you get hot water.
A study done by the Australian government found that tankless water heaters typically take 10 to 20 seconds longer to get hot water to a fixture than a corresponding storage type water heater and therefore led to significant water wastage.
For a green plumbing system we’ve pretty much eliminated traditional hot water circulating systems, warm water circulating systems, point of use water heaters in most situations, and tankless water heaters which waste water.
Hot water demand systems are energy efficient, water conserving, time saving, and green by any standards. Manufacturers of hot water demand systems include Metlund, Taco Pump, Chilipepper Sales, and others.
A demand hot water system typically consists of a small pump mounted under the sink furthest from the water heater exactly the same as most warm water circ systems. When you want hot water you push a start button and the pump speeds the water from your water heater to the fixture, routing the cooled off hot water left in the pipe from the last use back to the water heater through the cold water piping.
When hot water reaches the pump it shuts off, preventing putting hot water into the cold water line. The pump has a higher flow rate than most fixtures making the waiting time shorter than a normal residential hot water piping system. Since no water gets run down the drain you save water. Since the pump only runs when you actually want hot water and only runs for a few seconds it uses very little electricity. Typically for a family of 4 the pump uses $1-$2 per year.
No extra water heating energy is needed because the pump doesn’t circulate the water, it just gets it to the fixture and stops.
How you define instant hot water and how you obtain instant hot water make the difference between a water and energy wasting system and a truly green system like hot water demand systems.
Truly instant hot water would be for instance if you have a traditional full time hot water circulating system with the proper plumbing layout. You would have hot water immediately upon opening an hot water fixture or faucet, that being within 2 or 3 seconds anyway.
Obviously for convenience this would be the best scenario. However there is a high price to pay for such a system. By continuously circulating hot water through your hot water plumbing you are wasting a huge amount of energy. Using energy costs money and contributes to greenhouse gas emissions.
There are also circulating systems that utilize the cold water piping as a return line for the hot water circulating system. These systems which include the Laing, Grundfos, RedyTemp, Watts, and others, are what I call “warm water circulating systems”. These are temperature controlled recirc pumps that typically turn on the pump when the water temperature drops to 85 degrees, and then shuts off when the temperature reaches 95 degrees.
Like the hot water circulating systems these systems keep warmer than normal water in the piping causing an increase in energy usage and corresponding green house gas emissions. However, the water isn’t really hot, it’s warm to cool. Your body temperature is 98 degrees so the water might not even feel warm, perhaps “cool”. Anyway, you still have to run water down the drain to get “hot” water and you are wasting energy too. I would have a hard time calling these systems “green”.
Another method is to use a point of use water heater where the heater is located so close to the fixture that there is virtually no wait for the hot water. This is a green type of plumbing system. You don’t waste water running it down the drain waiting for hot water to arrive, and you don’t circulate hot water and waste all that energy.
However, point of use water heaters are not very useful in most residential settings. For one thing you would probably need more than one water heater, and that can be expensive.
Not much else you can do to have instant hot water. And even point of use water heaters don’t always get you instant hot water. For instance, if your point of use water heater is a tankless model then you once again will not have instant hot water. A tankless water heater typically requires the water to flow all the way through the heat exchanger to reach full temperature. This means that you have to purge water out of both the hot water piping and the water heater’s heat exchanger before you get hot water.
A study done by the Australian government found that tankless water heaters typically take 10 to 20 seconds longer to get hot water to a fixture than a corresponding storage type water heater and therefore led to significant water wastage.
For a green plumbing system we’ve pretty much eliminated traditional hot water circulating systems, warm water circulating systems, point of use water heaters in most situations, and tankless water heaters which waste water.
Hot water demand systems are energy efficient, water conserving, time saving, and green by any standards. Manufacturers of hot water demand systems include Metlund, Taco Pump, Chilipepper Sales, and others.
A demand hot water system typically consists of a small pump mounted under the sink furthest from the water heater exactly the same as most warm water circ systems. When you want hot water you push a start button and the pump speeds the water from your water heater to the fixture, routing the cooled off hot water left in the pipe from the last use back to the water heater through the cold water piping.
When hot water reaches the pump it shuts off, preventing putting hot water into the cold water line. The pump has a higher flow rate than most fixtures making the waiting time shorter than a normal residential hot water piping system. Since no water gets run down the drain you save water. Since the pump only runs when you actually want hot water and only runs for a few seconds it uses very little electricity. Typically for a family of 4 the pump uses $1-$2 per year.
No extra water heating energy is needed because the pump doesn’t circulate the water, it just gets it to the fixture and stops.
How you define instant hot water and how you obtain instant hot water make the difference between a water and energy wasting system and a truly green system like hot water demand systems.
Flushing Your Water Heater and the Truth about Sediment
Is your water heater making odd noises? Does it seem you run out of hot water sooner than you used to? Maybe it’s time to flush the sediment out of your water heater.
I often see it stated that a build up of sediment in the bottom of your gas water heater leads to lower efficiency. This would at first seem to make sense. The flames are heating the bottom of the tank, and if there is a thick layer of sediment then maybe it would be harder to heat the water in the tank and lead to lower efficiency.
However, I read somewhere that a buildup of sediment does not impact the efficiency of the water heater. I believe it was a study done by Battelle Labs, but I don’t remember for sure. The study found that there was no significant reduction in water heater efficiency with a buildup of sediment.
If you think about it carefully it makes perfect sense. The flames still transfer their heat to the metal bottom of the tank, which is wetted on the inside of the tank, and thus the heat is transferred into the tank at the same efficiency. The difference is some of the material being heated is sediment, which will impart that heat to the water it’s in.
Hence there is no real loss of efficiency. There may be less water available to use since sediment does displace volume, but with no impact on water heater efficiency. However, if you don’t live in an area with hard water you probably won’t accumulate enough sediment to make a noticeable difference in the capacity of your hot water heater.
There are noises that gas water heaters can produce as a result of mineral deposits or sediment buildup, like gurgling, popping and banging noises. This is caused by the heat from the burner causing some of the water sitting against the bottom of the tank to turn into steam bubbles. As the bubbles work their way up through the sediment they can produce all sorts of odd noises.
The solution is to flush the sediment out of the heater.
With electric water heaters the elements can become incrusted with mineral deposits which can flake off and contribute to sediment buildup. With electric water heaters the buildup of minerals on the heating elements does not cause a decrease in efficiency. The heat generated by the heating elements still ends up inside the tank, so no decrease in efficiency. The buildup can however lead to higher temperatures in the elements and cause premature failure of the heating elements.
Tankless water heaters can also suffer from scale buildup in the heat exchanger. Obviously sediment buildup is not a problem for tankless water heaters, but scale build is. The buildup of scale on the heat exchanger can lead to reduced water flow causing the heat exchanger to over heat which will lead to problems.
In fact, if you read the owner’s manuals you will find that most tankless water heater manufactures specify the maximum hardness of water that you can use the unit with and still have a valid warranty. Too hard and the warranty is void. In those cases they recommend using a water softener.
Most also recommend that you de-scale your water heater periodically to prevent the buildup of scale. I think they have you run vinegar through it or something. I can’t exactly remember and I am too lazy to go look. From reading the owners manual it doesn’t sound like anything I would want to spend my Saturday afternoon doing.
Another area where sediment and scale are a problem is with hot water recirc systems. Hot water recirc or recirculating systems pump hot water for long periods of time and thus suffer from scale buildup. This is probably the primary reason for recirc pump failures.
Hot water demand systems such as the Chilipepper, Metlund D’mand System, and the Armstrong system, do not suffer from scale because they don’t really circulate hot water. Since the pumps shut off as the hot water arrives, they never really pump water that is actually hot, and they never run for long periods of time with hot water in them. Hot water is the culprit to blame for scale buildup, and so demand systems simply don’t have a scale buildup problem.
If you need to flush the sediment from your water heater: Flushing Your Water Heater
I often see it stated that a build up of sediment in the bottom of your gas water heater leads to lower efficiency. This would at first seem to make sense. The flames are heating the bottom of the tank, and if there is a thick layer of sediment then maybe it would be harder to heat the water in the tank and lead to lower efficiency.
However, I read somewhere that a buildup of sediment does not impact the efficiency of the water heater. I believe it was a study done by Battelle Labs, but I don’t remember for sure. The study found that there was no significant reduction in water heater efficiency with a buildup of sediment.
If you think about it carefully it makes perfect sense. The flames still transfer their heat to the metal bottom of the tank, which is wetted on the inside of the tank, and thus the heat is transferred into the tank at the same efficiency. The difference is some of the material being heated is sediment, which will impart that heat to the water it’s in.
Hence there is no real loss of efficiency. There may be less water available to use since sediment does displace volume, but with no impact on water heater efficiency. However, if you don’t live in an area with hard water you probably won’t accumulate enough sediment to make a noticeable difference in the capacity of your hot water heater.
There are noises that gas water heaters can produce as a result of mineral deposits or sediment buildup, like gurgling, popping and banging noises. This is caused by the heat from the burner causing some of the water sitting against the bottom of the tank to turn into steam bubbles. As the bubbles work their way up through the sediment they can produce all sorts of odd noises.
The solution is to flush the sediment out of the heater.
With electric water heaters the elements can become incrusted with mineral deposits which can flake off and contribute to sediment buildup. With electric water heaters the buildup of minerals on the heating elements does not cause a decrease in efficiency. The heat generated by the heating elements still ends up inside the tank, so no decrease in efficiency. The buildup can however lead to higher temperatures in the elements and cause premature failure of the heating elements.
Tankless water heaters can also suffer from scale buildup in the heat exchanger. Obviously sediment buildup is not a problem for tankless water heaters, but scale build is. The buildup of scale on the heat exchanger can lead to reduced water flow causing the heat exchanger to over heat which will lead to problems.
In fact, if you read the owner’s manuals you will find that most tankless water heater manufactures specify the maximum hardness of water that you can use the unit with and still have a valid warranty. Too hard and the warranty is void. In those cases they recommend using a water softener.
Most also recommend that you de-scale your water heater periodically to prevent the buildup of scale. I think they have you run vinegar through it or something. I can’t exactly remember and I am too lazy to go look. From reading the owners manual it doesn’t sound like anything I would want to spend my Saturday afternoon doing.
Another area where sediment and scale are a problem is with hot water recirc systems. Hot water recirc or recirculating systems pump hot water for long periods of time and thus suffer from scale buildup. This is probably the primary reason for recirc pump failures.
Hot water demand systems such as the Chilipepper, Metlund D’mand System, and the Armstrong system, do not suffer from scale because they don’t really circulate hot water. Since the pumps shut off as the hot water arrives, they never really pump water that is actually hot, and they never run for long periods of time with hot water in them. Hot water is the culprit to blame for scale buildup, and so demand systems simply don’t have a scale buildup problem.
If you need to flush the sediment from your water heater: Flushing Your Water Heater
Friday, July 16, 2010
Water Heating Methods; Solar, Tankless, Storage, Point-of-Use, or Heat Pump
The list of water heating methods is a long one, natural gas, propane, electric resistance, wood burning, boiler, and passive solar, active solar, geothermal, and heat pumps.
For this article I’m not going to get into the more exotic water heating methodologies, I’ll stick to the more common methods of heating water for residential settings.
Solar Hot Water Heating
Solar water heating systems can be a great bargain, provide inexpensive or even free water heating, or on the other hand they can be some of the most expensive and high maintenance system types. There are passive solar systems and active systems that require pumps and controllers etc.
Passive solar systems do not have a pump. They just sit there and do their thing with no moving parts. Active systems use pumps, valves, and controllers. Active solar heaters are more efficient and more costly than passive solar systems.
Solar water heating is very location dependent. Passive systems are better if not used in areas that freeze often or have hard freezes. Active systems can drain the water or use other methods to protect the system from freezing trouble. There are different types of passive systems. Batch systems are one type that are basically a tank mounted in a tiny green house.
Some passive systems use solar collectors. Solar collectors mounted lower than the tank can use natural thermal siphoning action to transfer the hot water to the storage tank. There are of course many variations.
If you live where freezing is a problem then you need an active system of which there are many varieties. Some heat the water directly, some use an anti-freeze solution in the collectors, some drain the water out of the system when it approaches freezing etc.
Storage Water Heating
Standard storage type gas and electric water heaters are hard to beat. They are simple, require virtually no maintenance, and seldom have problems. There are high efficiency gas water heater models that cost a little more but rival tankless on efficiency. They still have storage standby losses though. Standby losses probably amount to less than $5.00 a month realistically.
If something breaks down with a storage heater it’s easy to find the parts and just about any plumber or handyman can fix it. It’s an easy project for most do-it-yourselfers. And tank type water heaters usually fail by way of a tank leak. When you see a puddle under your water heater you know it’s time to purchase a new one. It gives you time to get it replaced without having to live for a few days without hot water.
Storage or tank type water heaters provide the hot water faster than tankless heaters since the water is already hot unlike the tankless units.
Heat Pump Water Heaters
Heat pump water heaters are a highly efficient method of water heating. Heat pump water heaters don’t have to make the heat as with other types of water heaters. They don’t work well in cold climates due to an insufficient amount of heat available in the environment around the heat pump.
Heat pumps work just like your air conditioner. A heat exchanger inside the tank heats the water and another heat exchanger outside pulls the heat out of the outside air. There just has to be sufficient heat in the surrounding air.
Heat pump water heaters are slower to heat water than electric resistance heaters or gas water heaters. As the water temperature increases and/or the outside air temperature decreases the heat pump heats the water even slower.
Heat pumps are much more expensive than standard electric water heaters and will be harder to find service for but they are sometimes a perfect solution where gas water heaters are not practical.
Heat pumps usually have a backup resistance heating element in the tank for those times when the outside temperature drops too low for the heat pump to work effectively.
Tankless Water Heaters
Tankless water heaters are hot products lately, presumably because they are a green, reducing the amount of energy you use to heat your hot water. Tankless water heaters do not have the standby losses inherent with tank type water heaters. The monetary savings isn’t all that much. You can probably save about $5.00 a month.
Gas tankless water heaters are much more common than electric tankless heaters. To heat water rapidly as a tankless heater must do it takes a whole lot of electricity. For a decent sized tankless heater you will need to run a dedicated wiring run and you might even need to upgrade the wiring from the power lines to your home. It gets very expensive.
Gas tankless water heaters also need significantly larger diameter venting than storage heaters do, and often it needs to be stainless steel which is pricy. The gas tankless heaters require a larger gas line than storage water heaters as well. That too can be expensive.
In order to start a tankless water heater, and to keep it on, you have to draw a minimum flow rate of ½ to ¾ gallons per minute of hot water. If you draw less than the minimum flow rate the water heater shuts off. Forget being able to run a trickle of hot water.
Tankless water heater need to be installed correctly. Failure to do so can result in problems that might not show up for years. Improperly draining the condensate can destroy the heat exchange which is expensive and won’t be covered under the warranty due to the improper drainage.
Point-of-Use Water Heating
Point of use water heaters are simply water heaters located very close to the fixture or fixtures they serve. They can be small tankless water heaters designed for small uses like hand washing and making tea, or they can be full water heaters of any type as long as they are located very close to the fixture. This pretty much eliminates the wasted water run down the drain while waiting for the hot water since there is virtually no wait with such a plumbing system.
Combination Systems
One can combine some of these water heating methods to save more water and energy making them even greener. You can use both a tankless water heater and a solar water heater hooked up together. You have inexpensive water heating and you won’t run out on those occasions when you need a large volume. If you combine systems you should be sure to check with the manufacturers because the equipment might not be compatible.
With any type of water heating you should check your local building codes and regulations before you change the type of water heater you are using.
For this article I’m not going to get into the more exotic water heating methodologies, I’ll stick to the more common methods of heating water for residential settings.
Solar Hot Water Heating
Solar water heating systems can be a great bargain, provide inexpensive or even free water heating, or on the other hand they can be some of the most expensive and high maintenance system types. There are passive solar systems and active systems that require pumps and controllers etc.
Passive solar systems do not have a pump. They just sit there and do their thing with no moving parts. Active systems use pumps, valves, and controllers. Active solar heaters are more efficient and more costly than passive solar systems.
Solar water heating is very location dependent. Passive systems are better if not used in areas that freeze often or have hard freezes. Active systems can drain the water or use other methods to protect the system from freezing trouble. There are different types of passive systems. Batch systems are one type that are basically a tank mounted in a tiny green house.
Some passive systems use solar collectors. Solar collectors mounted lower than the tank can use natural thermal siphoning action to transfer the hot water to the storage tank. There are of course many variations.
If you live where freezing is a problem then you need an active system of which there are many varieties. Some heat the water directly, some use an anti-freeze solution in the collectors, some drain the water out of the system when it approaches freezing etc.
Storage Water Heating
Standard storage type gas and electric water heaters are hard to beat. They are simple, require virtually no maintenance, and seldom have problems. There are high efficiency gas water heater models that cost a little more but rival tankless on efficiency. They still have storage standby losses though. Standby losses probably amount to less than $5.00 a month realistically.
If something breaks down with a storage heater it’s easy to find the parts and just about any plumber or handyman can fix it. It’s an easy project for most do-it-yourselfers. And tank type water heaters usually fail by way of a tank leak. When you see a puddle under your water heater you know it’s time to purchase a new one. It gives you time to get it replaced without having to live for a few days without hot water.
Storage or tank type water heaters provide the hot water faster than tankless heaters since the water is already hot unlike the tankless units.
Heat Pump Water Heaters
Heat pump water heaters are a highly efficient method of water heating. Heat pump water heaters don’t have to make the heat as with other types of water heaters. They don’t work well in cold climates due to an insufficient amount of heat available in the environment around the heat pump.
Heat pumps work just like your air conditioner. A heat exchanger inside the tank heats the water and another heat exchanger outside pulls the heat out of the outside air. There just has to be sufficient heat in the surrounding air.
Heat pump water heaters are slower to heat water than electric resistance heaters or gas water heaters. As the water temperature increases and/or the outside air temperature decreases the heat pump heats the water even slower.
Heat pumps are much more expensive than standard electric water heaters and will be harder to find service for but they are sometimes a perfect solution where gas water heaters are not practical.
Heat pumps usually have a backup resistance heating element in the tank for those times when the outside temperature drops too low for the heat pump to work effectively.
Tankless Water Heaters
Tankless water heaters are hot products lately, presumably because they are a green, reducing the amount of energy you use to heat your hot water. Tankless water heaters do not have the standby losses inherent with tank type water heaters. The monetary savings isn’t all that much. You can probably save about $5.00 a month.
Gas tankless water heaters are much more common than electric tankless heaters. To heat water rapidly as a tankless heater must do it takes a whole lot of electricity. For a decent sized tankless heater you will need to run a dedicated wiring run and you might even need to upgrade the wiring from the power lines to your home. It gets very expensive.
Gas tankless water heaters also need significantly larger diameter venting than storage heaters do, and often it needs to be stainless steel which is pricy. The gas tankless heaters require a larger gas line than storage water heaters as well. That too can be expensive.
In order to start a tankless water heater, and to keep it on, you have to draw a minimum flow rate of ½ to ¾ gallons per minute of hot water. If you draw less than the minimum flow rate the water heater shuts off. Forget being able to run a trickle of hot water.
Tankless water heater need to be installed correctly. Failure to do so can result in problems that might not show up for years. Improperly draining the condensate can destroy the heat exchange which is expensive and won’t be covered under the warranty due to the improper drainage.
Point-of-Use Water Heating
Point of use water heaters are simply water heaters located very close to the fixture or fixtures they serve. They can be small tankless water heaters designed for small uses like hand washing and making tea, or they can be full water heaters of any type as long as they are located very close to the fixture. This pretty much eliminates the wasted water run down the drain while waiting for the hot water since there is virtually no wait with such a plumbing system.
Combination Systems
One can combine some of these water heating methods to save more water and energy making them even greener. You can use both a tankless water heater and a solar water heater hooked up together. You have inexpensive water heating and you won’t run out on those occasions when you need a large volume. If you combine systems you should be sure to check with the manufacturers because the equipment might not be compatible.
With any type of water heating you should check your local building codes and regulations before you change the type of water heater you are using.
Tuesday, July 13, 2010
Upgrade Your Bathroom for Both Convenience and a Greener Lifestyle
Yes, you can upgrade your bathroom adding convenience and conserving significant amounts of water with no effort on the part of the user. It’s a home improvement project that will save you substantial amounts of water providing you with a greener lifestyle.
There are a lot of upgrades you can do to your bathroom these days that will result in an increased usage of water… walk in tubs, Jacuzzi tubs, multiple shower head showers etc. On the other hand things you do to save water are generally an inconvenience, like having to flush the toilet multiple times for it to work, having to wait for long periods to get hot water due to low flow fixtures, and showerheads that barely get you damp.
If you are planning a home improvement project or upgrade to your bathroom, there is a green plumbing product that will give you a greener lifestyle, something that will conserve water, save you time and money, and it will work great with all or any of your new bathroom equipment and fixtures.
It’s a hot water demand system. A small pump mounts under your sink. When you want hot water you press the start button and the pump speeds the hot water from your heater to your fixtures and doesn’t run any water down the drain in the process. You get hot water faster than normal and save a ton of water.
Hot water demand systems work with any kind of water heater including tankless water heaters, solar water heaters, gas water heaters, electric water heaters and heat pump water heaters. Any kind of fuel, propane, natural gas, electricity, fuel oil, or whatever is fine. The fuel type does not make any difference.
Note that this is a “demand” system that requires you push a button to get the pump going. Demand systems are green because they only run when you want hot water, not all the time. The resulting energy use is trivial coming in at around $1 - $2 per year to operate.
Since hot water isn’t circulated in the pipes you don’t use any more heating energy for the hot water than if you did not have the pump. It’s a win win, for both you and the environment.
The demand system is designed to get the hot water to the bathroom quickly without running water down the drain, but once it arrives at the bathroom the hard part is over and hot water is nearly instant at any of the bathroom fixtures. Once the hot water arrives and the pump has shut off, it is no longer in the flow path of the hot water. It will not affect your plumbing system when it isn’t running.
With the proper plumbing layout a hot water system can serve any number of fixtures by simply providing remote locations with a remote control start button. If your piping system loops from fixture to fixture then by putting the pump at the furthest fixture from the water heater it will provide fast hot water to all your fixtures with just the one pump.
Any bathroom would benefit from a hot water demand system as long as the water heater isn’t very close to the fixture. Point of use water heaters don’t really have a distribution system and with such minimal piping there isn’t really an advantage to having a hot water demand system, but everyone else needs one.
Help keep our planet green when doing a home improvement project or a bathroom upgrade, and by installing a hot water demand system. Imagine not having to stand in the bathroom in front of the bathroom shower with your hand in the stream waiting for the hot water to arrive on those chilly winter mornings.
The Chilipepper hot water demand pump is less than $200.00 and is easy to install. You don’t even need to shut off the water supply to the house, just the supply valves under the fixture where you wish to install the Chilipepper. You do however need an electrical outlet nearby to plug it into.
There are a lot of upgrades you can do to your bathroom these days that will result in an increased usage of water… walk in tubs, Jacuzzi tubs, multiple shower head showers etc. On the other hand things you do to save water are generally an inconvenience, like having to flush the toilet multiple times for it to work, having to wait for long periods to get hot water due to low flow fixtures, and showerheads that barely get you damp.
If you are planning a home improvement project or upgrade to your bathroom, there is a green plumbing product that will give you a greener lifestyle, something that will conserve water, save you time and money, and it will work great with all or any of your new bathroom equipment and fixtures.
It’s a hot water demand system. A small pump mounts under your sink. When you want hot water you press the start button and the pump speeds the hot water from your heater to your fixtures and doesn’t run any water down the drain in the process. You get hot water faster than normal and save a ton of water.
Hot water demand systems work with any kind of water heater including tankless water heaters, solar water heaters, gas water heaters, electric water heaters and heat pump water heaters. Any kind of fuel, propane, natural gas, electricity, fuel oil, or whatever is fine. The fuel type does not make any difference.
Note that this is a “demand” system that requires you push a button to get the pump going. Demand systems are green because they only run when you want hot water, not all the time. The resulting energy use is trivial coming in at around $1 - $2 per year to operate.
Since hot water isn’t circulated in the pipes you don’t use any more heating energy for the hot water than if you did not have the pump. It’s a win win, for both you and the environment.
The demand system is designed to get the hot water to the bathroom quickly without running water down the drain, but once it arrives at the bathroom the hard part is over and hot water is nearly instant at any of the bathroom fixtures. Once the hot water arrives and the pump has shut off, it is no longer in the flow path of the hot water. It will not affect your plumbing system when it isn’t running.
With the proper plumbing layout a hot water system can serve any number of fixtures by simply providing remote locations with a remote control start button. If your piping system loops from fixture to fixture then by putting the pump at the furthest fixture from the water heater it will provide fast hot water to all your fixtures with just the one pump.
Any bathroom would benefit from a hot water demand system as long as the water heater isn’t very close to the fixture. Point of use water heaters don’t really have a distribution system and with such minimal piping there isn’t really an advantage to having a hot water demand system, but everyone else needs one.
Help keep our planet green when doing a home improvement project or a bathroom upgrade, and by installing a hot water demand system. Imagine not having to stand in the bathroom in front of the bathroom shower with your hand in the stream waiting for the hot water to arrive on those chilly winter mornings.
The Chilipepper hot water demand pump is less than $200.00 and is easy to install. You don’t even need to shut off the water supply to the house, just the supply valves under the fixture where you wish to install the Chilipepper. You do however need an electrical outlet nearby to plug it into.
Using a Tankless Water Heater with a Hot Water Demand System
Tankless water heaters are considered a green plumbing product in that they can save energy over a conventional storage water heater since they don’t have the standby heat losses associated with the storage heaters.
However, tankless water heaters are not green when it comes to saving water. A study done by the Australian government, where there is a long running severe drought going, found that tankless water heaters took an average of 10 to 20 seconds longer to get hot water to the fixture than a storage type heater.
This is because with the storage heater the water leaving the outlet is piping hot. With a tankless water heater the water first leaving the outlet is cold…the water must pass through the heat exchanger first to get heated. So it takes longer to get hot water.
Longer waits for hot water mean more water run down the drain while you wait. The ideal solution is of course a hot water demand system. The hot water demand system will speed up the hot water and you won’t run any water down the drain while you wait. And hot water demand systems do not use much energy. A typical demand system uses about $2.00 per year in electricity, and can save a typical family of four persons over 10,000 gallons of water per year.
Not all demand systems are created equal
Tankless water heaters have a heat exchanger to transfer heat from the flames for a gas tankless water heater to the water, and the same goes for electric tankless water heaters. The heat exchanger is similar to the radiator in your car, water passes through tubes and becomes heated. It takes pressure to push water through pipes and tubes. The higher the flow the more pressure is required.
Tankless water heaters have pressure drops
Below is a graph showing the pressure drop VS. flow rate for several Rinnai tankless water heater models.
From the graph one can see that to obtain a flow rate of 3 gallon per minute the pump or source of water pressure would need to produce at least 9 feet of head for the two smallest heaters. (Its hard to read on this graph, but you can find it on the Rinnai site: http://www.rinnai.us/documentation/downloads/U287-077x0101.pdf)
9 feet of head is equal to 3.9 psi.
Hot Water Demand Systems Vs Pressure drops
Many brands of hot water demand systems have models that use Taco brand recirculation pumps, Taco model 006. Metlund D’mand sytems model S-50T uses a Taco 006 pump for instance. From the Taco pump curves in the second graph below you can see that the model 006 can’t produce enough pressure to overcome the back pressure at 3 gallons per minute.
Piping pressure drops
The hot water plumbing also has pipes. The piping well of course also have a pressure drop or back pressure.
A flow rate of 2 gallons per minute through 100 feet of ½" type L copper tubing creates a pressure drop of 2.8 psi, a 3 gallon per minute flow creates a 4.1 psi pressure drop, a 4 gallon per minute flow creates a 5.5 psi pressure drop.
So if your water heater has 100 feet of pipe from the water heater to the fixture, and another 100 feet to get back to the water heater inlet, then you need to add the pressure drop from the piping to the pressure drop for the heater plus the added pressure drops created by any check valves, elbows, and other fittings. We will ignore the fitting and valve drops and just consider piping and heater drops.
With a 3 gallon per minute flow rate the 200 feet of pipe would have a back pressure or pressure drop of 8.2 psi plus the heater’s 3.9 psi equals 12.1psi or 28 feet of head.
Metlund, Armstrong, and Taco demand systems
This eliminates the Taco 008 pump which can only produce about 15 feet of head maximum. That is the pump used by the Metlund model S-70T. The most powerful Metlund pump is the Metlund S-02T which uses the Taco 011 pump.
The Taco 011 has a maximum head of about 32 feet, so there had better not be many elbows and fittings for the water to flow through. When scale starts building up in the heat exchanger things will go down hill rapidly.
This is all fine if you want to wait longer for your hot water than without the demand system, you will still save the water!
Chilipepper hot water demand system
There are no pump curves available for the Chilipepper model CP6000, but it has a much more powerful motor (1/3) horsepower compared to Metlunds most powerful S-02T which is 1/8 of a horsepower and less efficient than the direct coupled Chilipepper pump. The Chilipepper pump is capable of producing a maximum pressure of about 50 to 60 psi (115 to 138 feet of head).
The maximum flow rate of the Chilipepper is 3 gallons per minute, but since it has so much pressure capability it typically pumps near its maximum with any piping system/tankless water heater combination.
When you go to the Metlund site and navigate to the specifications and see the Metlund models rated at 8 gpm for the smallest model on up to over 20 gpm for the S-02T you will now know that the specs are a bit misleading to say the least.
That 8 gallons per minute is how much water the pump could pump if nothing was hooked to the outlet. No back pressure!
If your plumbing layout has no pipes and no water heater the Metlund system will pump the water much faster than the Chilipepper, but if you have pipes and a water heater the Chilipepper will out perform the Metlund demand systems in nearly every case.
However, tankless water heaters are not green when it comes to saving water. A study done by the Australian government, where there is a long running severe drought going, found that tankless water heaters took an average of 10 to 20 seconds longer to get hot water to the fixture than a storage type heater.
This is because with the storage heater the water leaving the outlet is piping hot. With a tankless water heater the water first leaving the outlet is cold…the water must pass through the heat exchanger first to get heated. So it takes longer to get hot water.
Longer waits for hot water mean more water run down the drain while you wait. The ideal solution is of course a hot water demand system. The hot water demand system will speed up the hot water and you won’t run any water down the drain while you wait. And hot water demand systems do not use much energy. A typical demand system uses about $2.00 per year in electricity, and can save a typical family of four persons over 10,000 gallons of water per year.
Not all demand systems are created equal
Tankless water heaters have a heat exchanger to transfer heat from the flames for a gas tankless water heater to the water, and the same goes for electric tankless water heaters. The heat exchanger is similar to the radiator in your car, water passes through tubes and becomes heated. It takes pressure to push water through pipes and tubes. The higher the flow the more pressure is required.
Tankless water heaters have pressure drops
Below is a graph showing the pressure drop VS. flow rate for several Rinnai tankless water heater models.
From the graph one can see that to obtain a flow rate of 3 gallon per minute the pump or source of water pressure would need to produce at least 9 feet of head for the two smallest heaters. (Its hard to read on this graph, but you can find it on the Rinnai site: http://www.rinnai.us/documentation/downloads/U287-077x0101.pdf)
9 feet of head is equal to 3.9 psi.
Hot Water Demand Systems Vs Pressure drops
Many brands of hot water demand systems have models that use Taco brand recirculation pumps, Taco model 006. Metlund D’mand sytems model S-50T uses a Taco 006 pump for instance. From the Taco pump curves in the second graph below you can see that the model 006 can’t produce enough pressure to overcome the back pressure at 3 gallons per minute.
Piping pressure drops
The hot water plumbing also has pipes. The piping well of course also have a pressure drop or back pressure.
A flow rate of 2 gallons per minute through 100 feet of ½" type L copper tubing creates a pressure drop of 2.8 psi, a 3 gallon per minute flow creates a 4.1 psi pressure drop, a 4 gallon per minute flow creates a 5.5 psi pressure drop.
So if your water heater has 100 feet of pipe from the water heater to the fixture, and another 100 feet to get back to the water heater inlet, then you need to add the pressure drop from the piping to the pressure drop for the heater plus the added pressure drops created by any check valves, elbows, and other fittings. We will ignore the fitting and valve drops and just consider piping and heater drops.
With a 3 gallon per minute flow rate the 200 feet of pipe would have a back pressure or pressure drop of 8.2 psi plus the heater’s 3.9 psi equals 12.1psi or 28 feet of head.
Metlund, Armstrong, and Taco demand systems
This eliminates the Taco 008 pump which can only produce about 15 feet of head maximum. That is the pump used by the Metlund model S-70T. The most powerful Metlund pump is the Metlund S-02T which uses the Taco 011 pump.
The Taco 011 has a maximum head of about 32 feet, so there had better not be many elbows and fittings for the water to flow through. When scale starts building up in the heat exchanger things will go down hill rapidly.
This is all fine if you want to wait longer for your hot water than without the demand system, you will still save the water!
Chilipepper hot water demand system
There are no pump curves available for the Chilipepper model CP6000, but it has a much more powerful motor (1/3) horsepower compared to Metlunds most powerful S-02T which is 1/8 of a horsepower and less efficient than the direct coupled Chilipepper pump. The Chilipepper pump is capable of producing a maximum pressure of about 50 to 60 psi (115 to 138 feet of head).
The maximum flow rate of the Chilipepper is 3 gallons per minute, but since it has so much pressure capability it typically pumps near its maximum with any piping system/tankless water heater combination.
When you go to the Metlund site and navigate to the specifications and see the Metlund models rated at 8 gpm for the smallest model on up to over 20 gpm for the S-02T you will now know that the specs are a bit misleading to say the least.
That 8 gallons per minute is how much water the pump could pump if nothing was hooked to the outlet. No back pressure!
If your plumbing layout has no pipes and no water heater the Metlund system will pump the water much faster than the Chilipepper, but if you have pipes and a water heater the Chilipepper will out perform the Metlund demand systems in nearly every case.
Monday, July 12, 2010
Living with a Hot Water Demand System
Hot water demand systems are green plumbing products. They save tremendous amounts of water and they are a convenience for the homeowner or user of hot water.
Hot water demand systems work with any type of water heater, storage, tankless, solar, and even combination solar and tankless systems. Any type of water heater as long as the cold water inlet to the water heater is hooked to the same cold water supply as the cold water faucets at the fixtures.
However, they are quite dependent in their operation on the plumbing layout of your home. The hot water plumbing, cold water plumbing, and pump location can affect the demand system performance, and even cause some unusual behavior from the demand system.
Hot water demand systems consist of a small pump placed at the sink furthest from the water heater and connected to the hot and cold water supply lines. When you want hot water you “demand” it by pushing the start button. The pump speeds hot water from the water heater to the fixture, returning the cooled off hot water left in the hot water pipes from the last usage back to the water heater inlet through the cold water pipes.
When hot water reaches the pump an internal temperature sensor shuts the pump off to prevent filling the cold water lines with hot water. Now when you turn on the faucet you get nearly instant hot water and you didn’t run any water down the drain. The hot water was also delivered to you more quickly than by just running the faucet.
The demand systems shut the pumps off when they see a temperature rise, not at some absolute temperature. The reason for this is that it takes time for the heat to pass through the sensor housing and bring the temperature sensor itself up to the shut off temperature. By the time the sensor detects the full temperature of the water in the pump you will have filled the cold water line with hot water.
However, a sudden increase in temperature means hot water is just reaching the pump. Most hot water demand systems such as Metlund, Armstrong, and Taco use a 3 degree temperature increase to shut off the pump. The Chilipepper hot water demand system however has an adjustable temperature shut off. There is a knob on the front that you can use to adjust the shut off temperature increase between 3 degrees and 12 degrees.
One reason for an adjustable shut off temperature range is that sometimes due to the plumbing layout the demand system may shut off too soon. For instance, if the hot water pipe comes out of the water heater in the garage, goes through an interior wall, then passes through the center of an exterior wall and on to the bathroom. In the summer the exterior wall can heat up much warmer than the interior wall spaces and end up heating the hot water pipe due to the ambient temperature within the wall space.
The hot water demand system see’s a sudden increase in temperature from the warmed pipe and shuts off too soon. An adjustable off temperature can compensate for warm spaces that the pipes may pass through.
Typically, but not always, when you use hot water at the fixture you end up using mixed hot and cold water. This purges any warm water that the pump put into the cold water line before it shut off.
However, if the usage was entirely hot water with no cold water usage then there may remain some tepid water in the cold water line near the pump.
The hot water that remains in the hot water piping after a hot water usage event begins cooling immediately and cools at around 1-2 degrees per minute depending on the temperature of the hot water in the pipe, the amount of pipe insulation if any, and the ambient temperature.
If the hot water is normally at 140 degrees, which means that after a half hour it could still be at over 100 degrees. Since the pump won’t run unless the water temperature is less than 96 degrees, you won’t be able to use the system until it finishes cooling below 96 degrees.
Even so, you aren’t starting out with a pipe full of cold water so you should still get your hot water faster than normal, running less water down the drain than you would have if you didn’t have a demand system at all.
Because demand systems turn off once hot water reaches the pump, and the water begins cooling immediately, using the system with a timer can be problematic. You would want to use the hot water fairly soon after the timer activates the pump otherwise you may have plenty of warm water but still have to wait for hot.
Motion sensing can also be used to operate the pump, but keep in mind that with a motion sensor to activate the system you will activate the system more often than necessary. There potentially many times when someone may go into the bathroom and not need or want hot water.
Living with a hot water demand system is better than living without one!
Hot water demand systems work with any type of water heater, storage, tankless, solar, and even combination solar and tankless systems. Any type of water heater as long as the cold water inlet to the water heater is hooked to the same cold water supply as the cold water faucets at the fixtures.
However, they are quite dependent in their operation on the plumbing layout of your home. The hot water plumbing, cold water plumbing, and pump location can affect the demand system performance, and even cause some unusual behavior from the demand system.
Hot water demand systems consist of a small pump placed at the sink furthest from the water heater and connected to the hot and cold water supply lines. When you want hot water you “demand” it by pushing the start button. The pump speeds hot water from the water heater to the fixture, returning the cooled off hot water left in the hot water pipes from the last usage back to the water heater inlet through the cold water pipes.
When hot water reaches the pump an internal temperature sensor shuts the pump off to prevent filling the cold water lines with hot water. Now when you turn on the faucet you get nearly instant hot water and you didn’t run any water down the drain. The hot water was also delivered to you more quickly than by just running the faucet.
The demand systems shut the pumps off when they see a temperature rise, not at some absolute temperature. The reason for this is that it takes time for the heat to pass through the sensor housing and bring the temperature sensor itself up to the shut off temperature. By the time the sensor detects the full temperature of the water in the pump you will have filled the cold water line with hot water.
However, a sudden increase in temperature means hot water is just reaching the pump. Most hot water demand systems such as Metlund, Armstrong, and Taco use a 3 degree temperature increase to shut off the pump. The Chilipepper hot water demand system however has an adjustable temperature shut off. There is a knob on the front that you can use to adjust the shut off temperature increase between 3 degrees and 12 degrees.
One reason for an adjustable shut off temperature range is that sometimes due to the plumbing layout the demand system may shut off too soon. For instance, if the hot water pipe comes out of the water heater in the garage, goes through an interior wall, then passes through the center of an exterior wall and on to the bathroom. In the summer the exterior wall can heat up much warmer than the interior wall spaces and end up heating the hot water pipe due to the ambient temperature within the wall space.
The hot water demand system see’s a sudden increase in temperature from the warmed pipe and shuts off too soon. An adjustable off temperature can compensate for warm spaces that the pipes may pass through.
Typically, but not always, when you use hot water at the fixture you end up using mixed hot and cold water. This purges any warm water that the pump put into the cold water line before it shut off.
However, if the usage was entirely hot water with no cold water usage then there may remain some tepid water in the cold water line near the pump.
The hot water that remains in the hot water piping after a hot water usage event begins cooling immediately and cools at around 1-2 degrees per minute depending on the temperature of the hot water in the pipe, the amount of pipe insulation if any, and the ambient temperature.
If the hot water is normally at 140 degrees, which means that after a half hour it could still be at over 100 degrees. Since the pump won’t run unless the water temperature is less than 96 degrees, you won’t be able to use the system until it finishes cooling below 96 degrees.
Even so, you aren’t starting out with a pipe full of cold water so you should still get your hot water faster than normal, running less water down the drain than you would have if you didn’t have a demand system at all.
Because demand systems turn off once hot water reaches the pump, and the water begins cooling immediately, using the system with a timer can be problematic. You would want to use the hot water fairly soon after the timer activates the pump otherwise you may have plenty of warm water but still have to wait for hot.
Motion sensing can also be used to operate the pump, but keep in mind that with a motion sensor to activate the system you will activate the system more often than necessary. There potentially many times when someone may go into the bathroom and not need or want hot water.
Living with a hot water demand system is better than living without one!
Saturday, July 10, 2010
Green Living - Saving Water the Easy Way
Saving water is part of a green living lifestyle. There are a number of ways of saving water available to today’s homeowner. There are low flow fixtures and shower heads, low flow toilets, toilet dams, whole house leak detectors, drip irrigation for your garden, and water conserving appliances like dishwashers and washing machines.
Water Conservation Is Heavily Dependent Upon Human Behavior
Some of these water conservation measures are dubious at best, and others do a decent job. Overall, most water conservation methods, and products rely heavily on the behavior of the user to successfully conserve water.
Low flow showerheads and faucets are iffy at providing water savings. If you are concerned about how we treat our environment you probably already practice water conservation in such a way that the low flow fixtures have a minimal impact.
Low flow fixtures will not save you water when you fill a glass of water to drink, or when you fill a pot with water for cooking. It could save some water if when performing tasks such as washing your hands if you would have normally turned the faucet on to a higher flow rate than the low flow fixture allows.
If however you would normally run the fixture at the same flow rate as you use with the low flow fixture then it does not save you any water. Low flow fixtures save water for those people that would normally be water wasters.
Water conserving fixtures can even cause wastage of both water and energy. Take for example the occupant of a home who has a long hot water run from his water heater to his shower. The occupant is not going to get into the shower if the water is cold. He will wait for hot water to arrive first. Fast hot water saves water.
But many people turn on the shower and then go do something else rather than stand there with their hand in the running water. They might make the coffee or brush their teeth etc. When they return to the shower they find the hot water has arrived and they can get on with their shower. However, this means they were running heated water down the drain. Heating water costs far more than the water being heated. Heat is expensive and using that heat energy probably added to greenhouse gas emissions wherever it was generated in the case of electricity or at your water heater if it is gas operated.
Low flow fixtures can substantially increase the waiting time for hot water, and as a result more people engage in this behavior. Some people put a bucket under the shower and collect the water rather than let it run down the drain. They can then use it for toilet flushing, watering plants, etc. For individuals like these low flow shower heads are just a pain and not a worthwhile water conservation measure.
Even water conserving appliances are dependent upon human behavior to save water. The water conserving cycles are usually optional and therefore often ignored or forgotten about.
Hot water conservation results in both water conservation and energy conservation which makes it a good target for some kind of water conservation effort. In most homes the water heater is a significant distance from the fixture being used. This results in that aforementioned wait for hot water, and presents us with an opportunity for conservation.
Hot Water Demand System
Hot water demand systems are designed specifically to conserve water in the situations I have been describing above. The longer the distance from the fixture to the heater the more time water and money you can save.
The hot water demand systems consist typically of a small pump located under the fixture furthest from the source of hot water. When you desire (demand) hot water you simply push the start button and the pump speeds the hot water from your heater to your fixture without running water down the drain.
When hot water reaches the pump, the pump shuts off. Now the pipe between the water heater and the fixture is full of hot water and when you turn on the faucet you have nearly instant hot water and you didn’t run any down the drain.
Typically the pump will get the hot water to the fixture more quickly than if you run the faucet, especially with low flow fixtures. As with other measures there is an element of human behavior involved. But in this instance the incentive is to push the start button and not have to wait as long for the hot water.
The demand pump only runs for a few seconds, long enough to get the hot water to the fixture, and then shuts off, and thus uses very little energy. Typically the pump consumes less than $2.00 per year in electricity.
Saving Water the Easy Way
You will easily save water even if you have hundreds of feet of pipe from the water heater to the fixtures with a hot water demand system. You don’t need to put buckets under your fixtures to collect the normally wasted water. You don’t have to stand next to the shower with your hand in the stream waiting for the hot water to arrive. It’s easy, just push the start button.
A Green Home Improvement Product
Hot water demand systems make great green plumbing products for those interested in doing a home improvement project. The Chilipepper hot water demand system costs less than $200.00 and can be installed by anyone… no plumber needed, no soldering to do, it just hooks up with ordinary fixture supply hoses. You do however need an electrical outlet nearby. Often bathroom sinks don’t have an outlet under them, but typically an electrician or handyman can install one for $100 or so.
That small investment will bring you much appreciated convenience, save your water and possibly energy, and improve the resale value of your home. You can also feel good every time you use hot water because you are practicing green living and being kind to the environment.
Go green and install a hot water demand system in your home today!
Water Conservation Is Heavily Dependent Upon Human Behavior
Some of these water conservation measures are dubious at best, and others do a decent job. Overall, most water conservation methods, and products rely heavily on the behavior of the user to successfully conserve water.
Low flow showerheads and faucets are iffy at providing water savings. If you are concerned about how we treat our environment you probably already practice water conservation in such a way that the low flow fixtures have a minimal impact.
Low flow fixtures will not save you water when you fill a glass of water to drink, or when you fill a pot with water for cooking. It could save some water if when performing tasks such as washing your hands if you would have normally turned the faucet on to a higher flow rate than the low flow fixture allows.
If however you would normally run the fixture at the same flow rate as you use with the low flow fixture then it does not save you any water. Low flow fixtures save water for those people that would normally be water wasters.
Water conserving fixtures can even cause wastage of both water and energy. Take for example the occupant of a home who has a long hot water run from his water heater to his shower. The occupant is not going to get into the shower if the water is cold. He will wait for hot water to arrive first. Fast hot water saves water.
But many people turn on the shower and then go do something else rather than stand there with their hand in the running water. They might make the coffee or brush their teeth etc. When they return to the shower they find the hot water has arrived and they can get on with their shower. However, this means they were running heated water down the drain. Heating water costs far more than the water being heated. Heat is expensive and using that heat energy probably added to greenhouse gas emissions wherever it was generated in the case of electricity or at your water heater if it is gas operated.
Low flow fixtures can substantially increase the waiting time for hot water, and as a result more people engage in this behavior. Some people put a bucket under the shower and collect the water rather than let it run down the drain. They can then use it for toilet flushing, watering plants, etc. For individuals like these low flow shower heads are just a pain and not a worthwhile water conservation measure.
Even water conserving appliances are dependent upon human behavior to save water. The water conserving cycles are usually optional and therefore often ignored or forgotten about.
Hot water conservation results in both water conservation and energy conservation which makes it a good target for some kind of water conservation effort. In most homes the water heater is a significant distance from the fixture being used. This results in that aforementioned wait for hot water, and presents us with an opportunity for conservation.
Hot Water Demand System
Hot water demand systems are designed specifically to conserve water in the situations I have been describing above. The longer the distance from the fixture to the heater the more time water and money you can save.
The hot water demand systems consist typically of a small pump located under the fixture furthest from the source of hot water. When you desire (demand) hot water you simply push the start button and the pump speeds the hot water from your heater to your fixture without running water down the drain.
When hot water reaches the pump, the pump shuts off. Now the pipe between the water heater and the fixture is full of hot water and when you turn on the faucet you have nearly instant hot water and you didn’t run any down the drain.
Typically the pump will get the hot water to the fixture more quickly than if you run the faucet, especially with low flow fixtures. As with other measures there is an element of human behavior involved. But in this instance the incentive is to push the start button and not have to wait as long for the hot water.
The demand pump only runs for a few seconds, long enough to get the hot water to the fixture, and then shuts off, and thus uses very little energy. Typically the pump consumes less than $2.00 per year in electricity.
Saving Water the Easy Way
You will easily save water even if you have hundreds of feet of pipe from the water heater to the fixtures with a hot water demand system. You don’t need to put buckets under your fixtures to collect the normally wasted water. You don’t have to stand next to the shower with your hand in the stream waiting for the hot water to arrive. It’s easy, just push the start button.
A Green Home Improvement Product
Hot water demand systems make great green plumbing products for those interested in doing a home improvement project. The Chilipepper hot water demand system costs less than $200.00 and can be installed by anyone… no plumber needed, no soldering to do, it just hooks up with ordinary fixture supply hoses. You do however need an electrical outlet nearby. Often bathroom sinks don’t have an outlet under them, but typically an electrician or handyman can install one for $100 or so.
That small investment will bring you much appreciated convenience, save your water and possibly energy, and improve the resale value of your home. You can also feel good every time you use hot water because you are practicing green living and being kind to the environment.
Go green and install a hot water demand system in your home today!
Green Plumbing Products – An Evaluation of Water and Energy Conservation Methods and Devices
There are a number of plumbing products on the market that claim they are green. Some are, and some probably are not. I’m going to provide my biased opinion about just how green some of these products are, then you can decide for yourself what is green and what isn’t.
First let’s define what a green product is. My feeling is that to call your product green it should either reduce the amount of energy being used for a specific task, conserve natural resources such as water, or in some other way have a beneficial impact on our environment.
One has to be careful in evaluating energy conserving, water conserving, or other types of “green plumbing products” to examine all aspects of the method or device being considered. It’s quite possible for a product to have a beneficial side and a negative side at the same time. One has to weigh both the benefits and negative aspects of a product.
I have a hypothesis about green plumbing products. I suspect they will depend heavily on user behavior to meet their goal of being green. I shall take that aspect into account in my analysis.
Years ago when I had a vested interest in the California’s Title 24 building codes to help me market an energy saving product. The CEC (California Energy Commission) had commissioned a study that revealed the human behavior problems inherent in many conservation methods and devices.
For instance, it was found that most homes did not save much energy with set back thermostats because the users were not using them properly. The study found that after installing dual pane windows, extra insulation, and making the house air tight, people would turn on the air conditioners and leave the window open, defeating virtually all the energy conservation features that had been added to the home.
Low Flow Showerheads
Low flow shower heads are a good example of water conservation devices that save water but can suffer from human behavior problems. Low flow shower heads when located far from the source of hot water end up causing a long wait for hot water, often exceeding several minutes.
Many people will turn on the shower to hot and let it run while they do something else, like make the coffee, or shave, and upon completing the task they return to check and see if the water is hot yet. When it is, it means you have not only been running precious water down the drain, but you are also dumping heated water. Heating the water uses energy and thus likely contributes to green house gas emissions, unless you are using electric water heating and are being supplied your electrical energy by a wind farm.
If, however, you are one of those environmentally conscious individuals who truly does their best to live a conservative lifestyle, then you probably will not benefit from a low flow shower head. You would probably not turn it up to full blast and spend 20 minutes in the shower. Low flow showerheads are a way of forcing wasteful people to be less wasteful.
I imagine overall it does save water, mostly with individuals like me who tend to really enjoy taking long, hot, high-volume showers. Now they are long, hot, and low volume.
I rate the low-flow showerhead a green plumbing product. Overall it saves both water and energy with minimal human behavior problems associated with it.
Low Flow Toilets
How about those low-flow toilets? I keep hearing that they finally have some that really do work well, but my experience is you often need to flush multiple times defeating the original purpose. If there are models that truly work out there then I don’t see any downside to them.
I rate the low-flow toilets as a green plumbing product, if they work. For me the jury is still out.
Tankless Water Heaters
How about tankless water heaters? They are certainly touted to be green plumbing products… they supposedly save you a ton of energy. I think we should take a closer look.
Tankless water heaters work quite differently than standard tank type storage water heaters. When you turn on the faucet and you have a storage water heater the hot water immediately flows from the water heater outlet to the fixture. The water is coming from the top of the tank where it is the hottest. As the water travels though the cold pipe, the pipe absorbs the heat from the water until it reaches equilibrium.
If your pipe holds a gallon of water between the water heater and the fixture, then it might take you a gallon and a half to get hot water due to this affect. The colder the ambient temperature around the hot water pipes the larger the effect.
Now let’s see what happens with a tankless water heater. When you turn on the fixture you are also turning on the tankless heater which has a flow switch to detect the flow of hot water and thus turn on the heater in response.
The water that immediately begins flowing thought the pipe is not hot. It has been sitting in the heat exchanger and is cold. For the water leaving the outlet to be at full temperature it must flow completely through the heat exchanger.
According to a study done by the Australian government, tankless water heaters typically require 10 to 20 seconds longer to get hot water to the fixture than storage tank type water heaters. This is obviously a negative since you will be running more water down the drain while you wait longer for your hot water to arrive. Now if your water heater is only 6 feet from the fixture it isn’t much of a problem. But if the heater is 100 feet from the fixture it is a big problem. A typical family of four can waste over 10,000 gallons of water a year waiting for hot water to arrive.
There is another water conservation problem with tankless water heaters. Remember that flow switch? It won’t turn on the hot water heater unless it detects a minimum flow rate, typically ½ gallon per minute, and ¾ gallons per minute for the larger models. This means that if you use less than ½ gallon per minute of hot water the heater will shut down. Think about that for a moment, if your fixture is 1-1/2 gallons per minute as many fixtures are, you will need to run the faucet at over half of full volume even if you only want a trickle of hot water.
Not only will you be wasting water, but heated water. Heating the water is far more expensive that the water itself. And there are the resulting green house gas releases as well. Not a very green aspect to tankless water heaters.
Human behavior is a big factor with tankless heaters. For one thing, people who like to take long showers will. That could lead to substantially higher water usage and of course, energy usage. Humans are like that.
Like with the solar industry, tankless water heaters won’t end up saving you money if there weren’t big tax incentives. When the tax incentives were eliminated for the solar water heating industry it collapsed. I think that will happen with tankless eventually as well, but that is only my opinion and I am not particularly good at predicting the future.
My opinion… Tankless water heaters are not very green plumbing products.
Hot Water Demand Systems
Hot water demand systems usually consist of a small pump mounted under the sink. The pump connects between the hot and cold water lines. When you want hot water you push a start button, the pump comes on and pumps the hot water from your water heater to your fixture at high speed. When hot water reaches the pump it shuts off to keep hot water from getting into the cold water line.
The cooled-off hot water in the hot water pipes gets returned to the water heater inlet though the cold water piping. You get your hot water faster than normal, and no hot water gets run down the drain.
Hot water demand systems will work with storage water heaters, tankless water heaters, and even solar water heaters. They run only for a few seconds at a time, just long enough to get hot water to the fixture, so they use very little energy, typically less than $2.00 per year.
Human beings for the most part do not like standing around waiting for the hot water to arrive. This means that they will usually use the hot water demand system when it’s available. It’s a convenience and humans love convenience. If they don’t push the button is the same as not having one installed.
Hot water demand systems have few if any negatives. You get your hot water faster and you save water with virtually no increase in energy consumption… what more could you ask for?
I rate the hot water demand system as a very green plumbing product.
First let’s define what a green product is. My feeling is that to call your product green it should either reduce the amount of energy being used for a specific task, conserve natural resources such as water, or in some other way have a beneficial impact on our environment.
One has to be careful in evaluating energy conserving, water conserving, or other types of “green plumbing products” to examine all aspects of the method or device being considered. It’s quite possible for a product to have a beneficial side and a negative side at the same time. One has to weigh both the benefits and negative aspects of a product.
I have a hypothesis about green plumbing products. I suspect they will depend heavily on user behavior to meet their goal of being green. I shall take that aspect into account in my analysis.
Years ago when I had a vested interest in the California’s Title 24 building codes to help me market an energy saving product. The CEC (California Energy Commission) had commissioned a study that revealed the human behavior problems inherent in many conservation methods and devices.
For instance, it was found that most homes did not save much energy with set back thermostats because the users were not using them properly. The study found that after installing dual pane windows, extra insulation, and making the house air tight, people would turn on the air conditioners and leave the window open, defeating virtually all the energy conservation features that had been added to the home.
Low Flow Showerheads
Low flow shower heads are a good example of water conservation devices that save water but can suffer from human behavior problems. Low flow shower heads when located far from the source of hot water end up causing a long wait for hot water, often exceeding several minutes.
Many people will turn on the shower to hot and let it run while they do something else, like make the coffee, or shave, and upon completing the task they return to check and see if the water is hot yet. When it is, it means you have not only been running precious water down the drain, but you are also dumping heated water. Heating the water uses energy and thus likely contributes to green house gas emissions, unless you are using electric water heating and are being supplied your electrical energy by a wind farm.
If, however, you are one of those environmentally conscious individuals who truly does their best to live a conservative lifestyle, then you probably will not benefit from a low flow shower head. You would probably not turn it up to full blast and spend 20 minutes in the shower. Low flow showerheads are a way of forcing wasteful people to be less wasteful.
I imagine overall it does save water, mostly with individuals like me who tend to really enjoy taking long, hot, high-volume showers. Now they are long, hot, and low volume.
I rate the low-flow showerhead a green plumbing product. Overall it saves both water and energy with minimal human behavior problems associated with it.
Low Flow Toilets
How about those low-flow toilets? I keep hearing that they finally have some that really do work well, but my experience is you often need to flush multiple times defeating the original purpose. If there are models that truly work out there then I don’t see any downside to them.
I rate the low-flow toilets as a green plumbing product, if they work. For me the jury is still out.
Tankless Water Heaters
How about tankless water heaters? They are certainly touted to be green plumbing products… they supposedly save you a ton of energy. I think we should take a closer look.
Tankless water heaters work quite differently than standard tank type storage water heaters. When you turn on the faucet and you have a storage water heater the hot water immediately flows from the water heater outlet to the fixture. The water is coming from the top of the tank where it is the hottest. As the water travels though the cold pipe, the pipe absorbs the heat from the water until it reaches equilibrium.
If your pipe holds a gallon of water between the water heater and the fixture, then it might take you a gallon and a half to get hot water due to this affect. The colder the ambient temperature around the hot water pipes the larger the effect.
Now let’s see what happens with a tankless water heater. When you turn on the fixture you are also turning on the tankless heater which has a flow switch to detect the flow of hot water and thus turn on the heater in response.
The water that immediately begins flowing thought the pipe is not hot. It has been sitting in the heat exchanger and is cold. For the water leaving the outlet to be at full temperature it must flow completely through the heat exchanger.
According to a study done by the Australian government, tankless water heaters typically require 10 to 20 seconds longer to get hot water to the fixture than storage tank type water heaters. This is obviously a negative since you will be running more water down the drain while you wait longer for your hot water to arrive. Now if your water heater is only 6 feet from the fixture it isn’t much of a problem. But if the heater is 100 feet from the fixture it is a big problem. A typical family of four can waste over 10,000 gallons of water a year waiting for hot water to arrive.
There is another water conservation problem with tankless water heaters. Remember that flow switch? It won’t turn on the hot water heater unless it detects a minimum flow rate, typically ½ gallon per minute, and ¾ gallons per minute for the larger models. This means that if you use less than ½ gallon per minute of hot water the heater will shut down. Think about that for a moment, if your fixture is 1-1/2 gallons per minute as many fixtures are, you will need to run the faucet at over half of full volume even if you only want a trickle of hot water.
Not only will you be wasting water, but heated water. Heating the water is far more expensive that the water itself. And there are the resulting green house gas releases as well. Not a very green aspect to tankless water heaters.
Human behavior is a big factor with tankless heaters. For one thing, people who like to take long showers will. That could lead to substantially higher water usage and of course, energy usage. Humans are like that.
Like with the solar industry, tankless water heaters won’t end up saving you money if there weren’t big tax incentives. When the tax incentives were eliminated for the solar water heating industry it collapsed. I think that will happen with tankless eventually as well, but that is only my opinion and I am not particularly good at predicting the future.
My opinion… Tankless water heaters are not very green plumbing products.
Hot Water Demand Systems
Hot water demand systems usually consist of a small pump mounted under the sink. The pump connects between the hot and cold water lines. When you want hot water you push a start button, the pump comes on and pumps the hot water from your water heater to your fixture at high speed. When hot water reaches the pump it shuts off to keep hot water from getting into the cold water line.
The cooled-off hot water in the hot water pipes gets returned to the water heater inlet though the cold water piping. You get your hot water faster than normal, and no hot water gets run down the drain.
Hot water demand systems will work with storage water heaters, tankless water heaters, and even solar water heaters. They run only for a few seconds at a time, just long enough to get hot water to the fixture, so they use very little energy, typically less than $2.00 per year.
Human beings for the most part do not like standing around waiting for the hot water to arrive. This means that they will usually use the hot water demand system when it’s available. It’s a convenience and humans love convenience. If they don’t push the button is the same as not having one installed.
Hot water demand systems have few if any negatives. You get your hot water faster and you save water with virtually no increase in energy consumption… what more could you ask for?
I rate the hot water demand system as a very green plumbing product.
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