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The future of heat pumps....

Post in 'The Green Room' started by woodgeek, Mar 16, 2013.

  1. woodgeek

    woodgeek Minister of Fire

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  2. Circus

    Circus Member

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    Been investigating wall sleeve air source heat pump/ac. After digging I've found the heating mode is often just electrical resistance. There must be an easy way to tell which is which other than comparing the watts used. What are good HSPF SEER numbers?
    PS I know my climate is sometimes to cold for eff ASHP but it often isn't to cold.
  3. woodgeek

    woodgeek Minister of Fire

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    It seems american made old tech ASHPs run up to HSPF=8-9, mini-splits from asia appear to run 10-12. Actual performance would lag those values in a climate north of the mason dixon line. Near freezing, I would expect COP = 2 for a conventional split, and maybe 3 (??) for a mini.
  4. Highbeam

    Highbeam Minister of Fire

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    Anymore, the idea of "too cold" is old fashioned. In the old days and with old tech equipment this is a real problem. These days many units make full rated output well into the single digits. If you know you live in a cold place then you can oversize the unit and even if your system is only making 50% of rated output with a COP of 2 you are still warm and saving 50% of your money vs. resistance.
    woodgeek likes this.
  5. Circus

    Circus Member

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    Here, when it's coldish, it's sunny and the solar works well. When it's warmish, it's cloudy and I think the ASHP would work well. What is "old tech"? Any brand or model suggestions? I'd like to just replace a sleeved AC unit and be done with it.
  6. woodgeek

    woodgeek Minister of Fire

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    Sounds like you want a minisplit....I don't own one, so I would let others make their recommendation. By old tech, I mean a system that looks like central AC, with ductwork....that is what I have, and the efficiency is lower, and it sound like not what you are looking for.
    Circus likes this.
  7. begreen

    begreen Mooderator Staff Member

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    Old tech is older compressor technology, typically connected to a central HVAC system via an air handler and ductwork. What you are describing is a ductless system or mini-split. These typically have 1, 2 or 3 interior wall units that look like a wide air conditioner. The new tech in these units have an inverter compressor in the outdoor unit. In your climate I would look at the Mitsubishi Hi-Heat units unless the area is small. If so, a Fujitsu Halcyon unit might do.
    Circus likes this.
  8. Seasoned Oak

    Seasoned Oak Minister of Fire

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    Anyone investing in a new oil burner either has no other choice or for some reason thinks they can and want to afford heating oil for the next 25 years. Cost is already about $900 to fill a standard 275 gal tank.
  9. begreen

    begreen Mooderator Staff Member

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    There are plenty of areas where oil, propane or electric are the only heating choices. (Assuming that they don't want to deal with wood and solar is out). If delivered propane is still significantly higher and electricity is high then oil may be their best option. If oil goes up, propane will too. But many folks are still installing hot water heat. It is usually much more efficient than forced air. It's a tough choice and you are correct to point out that oil will just go up. But it's going to take time to wean ourselves off oil heat. Some folks have little choice.

    http://www.nytimes.com/2012/01/22/b...ortheast-cant-switch.html?pagewanted=all&_r=0

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