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  1. #1
    Join Date
    Jan 2014
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    Default Heat pump on my water heater. Should I turn it off in winter to save heat?

    My water heater has a heat pump on it. My house is heated by a force hot air propane furnace. It is in my cellar and it gets really cold down there from the cold air blowing from the heat pump. Should I change it to regular hot water to save on propane. When my heat comes on it blows really cold air first. The duct work is the cellar is always freezing.

  2. #2
    Join Date
    Jul 2010
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    SoCal
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    5,434

    Default Re: Heat pump on my water heater. Should I turn it off in winter to save heat?

    Sure, try it.

  3. #3
    Join Date
    Jan 2008
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    1,321

    Default Re: Heat pump on my water heater. Should I turn it off in winter to save heat?

    All forced air systems have a lag time before fully conditioned air reaches the registers, the ones furthest from the furnace have a lot of unconditioned air to displace before they begin heating or cooling. This is normal.

    Try the WH heat-pump switch and see what happens. Give it a month or two and compare bills from the same time last year. I wouldn't be surprised if you find quite a difference, even year round.

    It makes no sense to me to power a machine with electricity just to convert it's output to heat when the more direct approach has far less system efficiency loss. When you heat with electricity, nearly 100% of the power used turns into heat. The heat pump has to power the compressor then exchange heat and cold, and both processes have efficiency losses inherent in them. Factor in the extra cost of the heat pump and it may not be as good of an idea as it seems. I'd sure like to know what you find here to clear up my mind on that matter so please post your results in this thread afterward.

    Phil

  4. #4
    Join Date
    Aug 2007
    Location
    Maryland
    Posts
    1,254

    Default Re: Heat pump on my water heater. Should I turn it off in winter to save heat?

    The air in the ducts before the heat comes on will tend to take on the ambient temperature of the space they pass through. If the space is cold you could insulate the ducts there to minimize the heat loss.

  5. #5
    Join Date
    Jan 2014
    Posts
    15

    Default Re: Heat pump on my water heater. Should I turn it off in winter to save heat?

    I'll let you know what I find out. I do know the heat pump helps in the summer months with the air conditioning. Only had to turn it on AC a few days when temp was over 90 where I live we have maybe two heat waves where we get 90's 4 day in a row. First day my house is cool and I turn on AC the other 3. So maybe last year I only used it 6 days. It also helps that I have a old Victorian that is balloon framed with a huge maple tree on the south side for shade. My cellar is granite stone underground. Before this heat pump was installed even when I wasn't heating the house my cellar wouldn't go below freezing. I stored paint there when I was restoring this house. But with the heat pump and heating the upstairs the cellar does go below 32 degrees. My electric was great in the summer and still about the same in the winter so now I will see how much it goes up. I am paying $600 a month for propane in the winter. Will check out how much I pay this month with the heat pump off

  6. #6
    Join Date
    Jan 2014
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    15

    Default Re: Heat pump on my water heater. Should I turn it off in winter to save heat?

    Also will insulate the duct work

  7. #7
    Join Date
    Jan 2014
    Posts
    1

    Default Re: Heat pump on my water heater. Should I turn it off in winter to save heat?

    That is a very good question. The answer is yes and no. I am assuming that the heat pump water heater is the unitary type with the evaporator and compressor in a heated interior area. The cold air coming off the evaporator
    coil will cool that heated area. If that heated area is a basement for example and the heating thermostat is upstairs
    and the basement gets its heat from losses from duct work, and conduction through the floor, the resulting cool basement will consume a relatively small portion of the heat from the furnace. You will see higher relative humidity
    in the basement and condensate drip off of the cold evaporator as the cooler air has less moisture holding capacity.

    If the basement is heated as its own system, then shut the HPWH off in the heating season. Differences in fuel costs may drive you to a different conclusion. To get a meaningful comparison get the $/ BTU hour for the electricity and any other fuel you use.
    Remember that a BTU from the heat pump is about 1/2 the cost of a BTU from resistance heat. Get the oil or gas cost per BTU from the supplier. A good oil or gas furnace is probably 85% efficient on the average.

    Heat pump water heaters that discharge evaporator air into a heated area are having problems in northern climates.
    Some mfg. have optional air duct kits to take the air outside. One brand takes it from the outside and puts it back outside. Split system HPWH are an answer but more expensive and complicated to install and so far are missing from the North American market. At this time care and caution are in order.
    Last edited by Eaglebeak; 01-21-2014 at 08:22 AM. Reason: spelling and misstatement

  8. #8
    Join Date
    Jan 2014
    Posts
    15

    Default Re: Heat pump on my water heater. Should I turn it off in winter to save heat?

    Turned off the heat pump and just used the regular element. Electric went up $50 this month but not a full month. Haven't gotten propane bill yet to see if it went down. It would be fantastic if I could vent it to the outside but it is all one unit. What a great idea if I could, and then vent it inside in the summer. I love the summer when I hardly have to use the air conditioning. I should have looked into it more before I got it. There was probably one that you added to a regular tank that worked that way. I think my best bet is insulating the duct work if I want to use the heat pump in the winter. Lots of pros and cons to this. If I was living in a warmer climate I would highly recommend this water heater. But you are right living up north does make it challenging to figure out the best way to go.

  9. #9
    Join Date
    Jun 2007
    Location
    Fayette County, Ohio
    Posts
    5,620

    Default Re: Heat pump on my water heater. Should I turn it off in winter to save heat?

    You might enclose it in a foam board box vented to the out side for winter and inside for summer.

    Jack
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

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