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Tankless Water Heaters

2011 February 4

When I was doing some renovation in my sister’s small condominium apartment, she needed to design a layout that would create more space. She had a small water heater that was located underneath the left side of her sink. This is an area of the kitchen where most people would put a lazy susan.

She often complained that she could not take long showers or very hot baths during the winter due to her small water heater. I recommended that she look into getting a tankless water heater. I told her that they are commonly used in homes/flats in Europe and that they are great space savers and an energy efficient appliance that saves water, money and time.

Before she renovated her bathroom, she consulted with industry experts about the product. They recommended that she consider getting an additional appliance for the tankless water heater called the point-of-use or booster heater. This piece of equipment will generate a higher level of heat and maintain the heat level consistency during the winter months when the ground and underground pipes are cold.

She decided to purchase the tankless water heater and she has enjoyed it since. She told me that she noticed that her electric bill is about 10% less than she used to pay. She also was satisfied with the space she was able to save because right after she renovated her bathroom, she decided to renovate her kitchen and was able to get a lazy susan for the area of the kitchen where her water tank was previously located.

About the author:  Eric White works in the Office of Web Communications

Editor’s Note: The opinions expressed in Greenversations are those of the author. They do not reflect EPA policy, endorsement, or action, and EPA does not verify the accuracy or science of the contents of the blog.

Editor's Note: The opinions expressed in Greenversations are those of the author. They do not reflect EPA policy, endorsement, or action, and EPA does not verify the accuracy or science of the contents of the blog.

16 Responses leave one →
  1. Myron Katz permalink
    February 4, 2011

    Mistake. The most efficient way to heat water is with a Heat Pump water heater. It is not even close. Even saves operational costs as compared to a Solar Water heater for most people.
    The efficiency calculation does not include the ancillary benefit of 1/2 ton cooling/dehumidification. This is a NON TRIVIAL additional benefit.
    Of course you need a tank, but almost everyone has one. It can be very squat if you want it to be installed in a kitchen.
    Dehumidification is a benefit in almost all homes. This is especially true where i live: New Orleans.
    Moreover, a tankless water heater willl not even work if the input water temperature is too high. This is a persistent problem in the summer for tankless waterheaters installed where I live.

  2. EcoFriendlyEd permalink
    February 4, 2011

    It seems the tank is the issue in this particular situation. Tankless water heaters actually work very well if they are sized properly. They are rated by BTUs and GPM. Many people try to save a little on the unit only to find they can not get enough hot water. I find if you buy the model that has a slightly higher GMP than you require you wont have any issues. That being said my tankless operates on natural gas not electricity.
    The tankless water heater is especially efficient for me because my work requires me to travel often and I am only home 4-5 day a week. So the hot water is on demand and not keeping some tank hot all the time.

  3. Jim Bullis, Miastrada Co. permalink
    February 4, 2011

    Myron Katz,

    You make good points but also make a mistake.

    The most efficient way to heat water is with direct buring natural gas.

    Think of the whole problem where the electricity has to be made in a heat engine at a power plant, this is transferred to the heat pump which is just another heat engine running in reverse cycle. No way can there be as much heat coming out of the heat pump as went into the original heat engine.

    You might think of electricity as the equivalent of a very long bicycle chain that connects the shaft of one heat engine to the shaft of a heat pump.

    From an energy point of view, you might come out ahead if the apparatus keeps you from running an air conditioner.

  4. Jim Bullis, Miastrada Co. permalink
    February 4, 2011

    I misspoke by saying the heat pump is in reverse cycle compared to the heat engine.

    The process is reversed in the sense that heat makes mechanical energy in a heat engine and mechanical energy makes heat in a heat pump. That is not the same as reversing the cycle of an air conditioner, as is the case of the heat pump.

  5. Bob Bowen permalink
    February 5, 2011

    I live in a mobile home in California and have long been considering putting a tankless water heater in the kitchen area. The design of most mobile homes has the water heater toward the back of the home and on the opposite side of the home from the kitchen.The water (and natural gas) wasted getting warm or hot water to the kitchen and laundry area is enormous. Unfortunately this seems to be another of those “maybe someday” projects. Mainly because of the cost of the units.

  6. Steve permalink
    February 5, 2011

    “She also was satisfied with the space she was able to save because right after she renovated her bathroom, she decided to renovate her kitchen and was able to get a lazy susan for the area of the kitchen where her water tank was previously located.” I love that,

  7. David Bower permalink
    February 5, 2011

    I concur with Myron, I used to install a lot of tankless heater in the UK as a job when studying for my Masters in energy and sustainable development.
    Typically a tankless system will be only suitable for small amounts of water, certainly not taking a bath, it takes ages to fill and the fuel consumption is significantly more than a in tank heater system. Overall the energy and cost requirements are not what they claim to be dependant on the fuel type.
    In my fieldd tests the combination of linking and ground source pump, through a surface black mass (either at ground or roof based) increases efficiency expontentially.
    One other way which is marginally contentious is to use ground source cooling. The reson being by directly connecting the ground temp to the structures internal air temp a building can be held at 10 degrees C all year round by using a single 100w pump, then by swithching the room light on, a 100w bulb will heat the air temp to a comfortable social levell around 74F within minutes. However ir the building envelope has little thermal mass, cooling fights heating and energy costs increase.
    Ignore solar gain as it is like science, yes it can be calculated but usually the calcs do not bear a relationship to reality…

  8. Tim N permalink
    February 5, 2011

    even so…..several years ago i installed tankless heaters to several rental properties and am thrilled at the performance. Never a problem.
    This is not to say that heat pumps aren’t a good economecal solution to water heating because they are

  9. los gato Plumbing permalink
    March 16, 2012

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  10. plumbing los gatos permalink
    March 17, 2012

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  11. Paul Schlater permalink
    March 18, 2013

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  12. Rudy permalink
    July 2, 2013

    That all seems perfectly reasonable, Martin, and I don’t think those numbers surprise many of us who understand building science. If you’re using a tankless water heater for both space and water heating, however, I think the payback would be more favorable. I wonder if the research team has any plans to look at that system.

  13. william325 permalink
    September 28, 2013

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  14. Denver Tankless Water Heaters permalink
    November 4, 2013

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  15. angelineprincess5 permalink
    January 23, 2014

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  16. Denver water heaters permalink
    February 12, 2014

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