Heat Pump Water Heater

February 6th, 2010 by My Efficient Planet Leave a reply »

This is a heat pump water heater that I built, for heating potable hot water. It’s based on parts from a 10000BTU air conditioner, and various parts from the hardware store and refrigeration parts store. It provides about 3kw of heating capacity at 20C ambient temperature. The song at the end is Carpe Diem by Andy Timmons.

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11 comments

  1. TehMG says:

    On demand water heaters just save energy by eliminating standby heat losses.

    A heat pump system actually produces more heating power than the power required to run the system.

    For example, an electric heater with a 3kW element would produce 3kW of heat, while a heat pump system could produce 3kW of heat while only consuming 1kW of electricity.

    Nothing is more efficient than a heat pump system. The disadvantage is heat pumps do not perform well in very cold climates.

  2. legogunsmith says:

    why not just on demand electric hot water heater it would be more efficient ? sight glass on suction side it would be normal to see a mix depending on your evap function

  3. wtfwellington says:

    I’ve been thinking of making this all day! haha.

    have you thought of adding a safety-condenser for outside, when the heat of the water makes the high side pressure too high?

    like have it controlled by a duty high pressure switch and solenoid that would be on the beginning of the safety condenser, normally closed.

    I was just thinking before I saw this video that if this thing was actually made there would have to be a generous set of safeties to lengthen the life of the equipment.

  4. tesla500 says:

    Yes, it’s about 2 to 3 times as efficient as a heating element, depending on the outside air temperature.

  5. gavincurtis says:

    Just out of curiosity, is a heat pump design more efficient at heating water vs conventional submerged electric heating elements?

    Thanks.

  6. gavincurtis says:

    Very nice!

  7. tesla500 says:

    Thanks!

    I had this unit mostly complete about 2 years ago, but it just sat on my work bench taking up space. Recently the gas water tank blew, and I replaced it with an electric one, and got the motivation to complete this heat pump. It should be running in the next couple of days. I’ll have a video of the complete system soon.

  8. partypalooza5 says:

    I may have to build myself a system like this. Just got to find the parts now..

  9. Aussie50 says:

    Wow! really cool system!, I’m impressed!

  10. tesla500 says:

    Thanks!

    I used BBQ grade. I probably should have gotten the proper refrigerant grade, but you can’t beat the availability of BBQ grade.

    Both grades are pretty much equally flammable. Since the entire refrigeration system is outside in this case, I’m not too worried, any leaks would quickly dissipate instead of possibly pooling indoors. I also used sealed relays so there’s no source of ignition.

  11. partypalooza5 says:

    Really nice design! As far as the R290 is concerned, did you use BBQ grade or did you get the type designed to be a refrigerant? And if it is the refrigerant type is it still flammable?

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