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  1. #1
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    Default Hybrid water heater

    I saw Ask This Old House show the other day about hybrid water heaters but I have one BIG questions. Since they take heat out of the house aren't you paying twice to heat the water? But is does sound like it is dehumidifies the room so that could save that cost if installed in a basement. Any help what does it do to the heat in the room it is located?
    Last edited by mitch55; 03-01-2010 at 09:27 AM. Reason: miss spelling

  2. #2
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    Default Re: Hybrid water heater

    Quote Originally Posted by mitch55 View Post
    I saw Ask This Old House show the other day about hybrid water heaters but I have one BIG questions. Since they take heat out of the house aren't you paying twice to heat the water? But is does sound like it is dehumidifies the room so that could save that cost if installed in a basement. Any help what does it do to the heat in the room it is located?
    I'm guessing you're referring to the GE electric model.
    They don't take heat out of the house but rather use the ambient air within the home to asist with heating the water in the tank.
    My understanding is the unit on top acts as a heat pump/dehumidifier with the condensor coils surrounding the tank.
    "" an ounce of perception -- a pound of obscure "
    - Rush

  3. #3
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    Default Re: Hybrid water heater

    Quote Originally Posted by canuk View Post
    I'm guessing you're referring to the GE electric model.
    They don't take heat out of the house but rather use the ambient air within the home to asist with heating the water in the tank.
    My understanding is the unit on top acts as a heat pump/dehumidifier with the condensor coils surrounding the tank.
    Isn't the ambient air the heated air in the house? My understanding it works like a heat pump.

  4. #4
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    Default Re: Hybrid water heater

    Quote Originally Posted by mitch55 View Post
    Isn't the ambient air the heated air in the house? My understanding it works like a heat pump.
    Yes --- as previously posted.
    Since it takes in the ambient air extracts some heat then puts the air back into the room. I'm sure it's not a signifgant amount to impact the heating in the home.
    "" an ounce of perception -- a pound of obscure "
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  5. #5
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    Default Re: Hybrid water heater

    So they are using electric to run a compressor for the heat pump stage and then a heating element or two for the water heater itself? And this is supposed to be how much more efficient than a straight heating element heater?

    I'm thinking it may be more efficient to just have an un-insulated tempering tank fill with water to absorb room heat prior to filling the water heater - no electric needed for the tempering tank.

  6. #6
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    Default Re: Hybrid water heater

    I came to the same conclusion. If it takes heat out of the ambient air it is pumping cooled air back out into the house.I wonder if the lost heat from the house is figured into the cost calculations. Perhaps it evens out when it's hot outside.
    \Jack
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

  7. #7
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    Default Re: Hybrid water heater

    I have never seen such a bunch of marketing hype as this. GE should be ashamed of themselves for taking advantage of unsuspecting people that think they are going "green" here. The energy savings from any heat pump system is that it gets the heat for free from the outside air and pumps it into the home. While this is a bit more inefficient it still saves money because again the heat is free.
    In this case the heat is not free! They are taking the heat from the ambient air which has been heated by the home's heating system and putting into the tank. This heat is not free, it has been paid for in the cost of your heating bill.
    All they are doing here is ultimately just transferring some of the cost of heating the water from the hot water heater itself to your home's heating system. This is all in the name of going "green"? I would expect the total cost to actually be higher because of the cost of running the heat pump. GE, shame on you!!!

  8. #8
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    Default Re: Hybrid water heater

    I would question just how many folks have their waterheaters within the living space of the house to begin with. Yes, for those inside the house, the heat exchange waterheater probably isn't a good idea, though how much heat is really being pulled out of the ambient air, that was not made clear by the TOH program.

    What about those that DO NOT have the water heater inside the living space, but rather in an exterior closet, in the garage, or in an unfinished basement next to the furnace? In each of these cases, no heat at all is being removed from the house, and in the case of being placed next to the furnace, it is utilizing gobs of otherwise lost heat. Most of the homes in this area have the waterheater in the garage.

    So they are using electric to run a compressor for the heat pump stage and then a heating element or two for the water heater itself? And this is supposed to be how much more efficient than a straight heating element heater?
    According to the TOH broadcast, the primary heating comes from the heat exchanger, only under high demand do electric elements kick in to aid water recovery time.
    I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!

  9. #9
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    Default Re: Hybrid water heater

    Quote Originally Posted by rbperrie View Post
    . The energy savings from any heat pump system is that it gets the heat for free from the outside air and pumps it into the home. While this is a bit more inefficient it still saves money because again the heat is free.
    No offense but, your heat produced by your heat pump is not * free *.
    It costs however much electricity is used to produce the heat. The concept of heat transfer from the outside air is a fairly efficent system , albeit that efficency decreases the colder the outside air becomes.
    Generally the cost savings comes from not burning a fuel to produce heat, though that too changes when the outside air temperature decreases forcing a supplemental heat source needed for the heat pump.
    So , as you see your heat is not *free*.

    In this case the heat is not free! They are taking the heat from the ambient air which has been heated by the home's heating system and putting into the tank. This heat is not free, it has been paid for in the cost of your heating bill.
    All they are doing here is ultimately just transferring some of the cost of heating the water from the hot water heater itself to your home's heating system. This is all in the name of going "green"? I would expect the total cost to actually be higher because of the cost of running the heat pump
    The one point that needs to considered is the heated ambient air is not lost unlike the use of a bathroom or kitchen exhaust fan.
    It's true these water heaters use a heat pump type of system by intaking ambient air and transfering the exchanged heat to the water tank.The efficiency of heat transfer is what makes the concept of these systems an attractive alternative.
    These systems generally are using the hybrid system for maintaining the water temperature in the tank ,offsetting the need to use the electric elements inside an electric water heater. Instead the elements would be mostly used only for high use .

    I would have to say A. Spruce hit the nail on the head with some points. It's not likely that these water heaters will be anywhere that would be noticeable.
    They are somewhat new and little detailed information is lacking at this point regarding real world savings. What the actual savings will be is yet to be determined, but I doubt they will be what the manufacturers publish.

    Somewhere I had run across an article in which some folks that were involved in the intial trial run. I'll see if I can locate and post some feed back from those users.

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