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  1. #1

    Cold weather air source heat pumps

    I remember last spring reading somewhere that Mitsubishi (I believe) was developing a cold weather heat pump. Anyone know any details regarding other companies using this technology? Thanks.

  2. #2
    Join Date
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    They are all for use in cold weather.

    What type of application are you looking for? Do yu live in Antarctica or something?
    How tall are you Private???!!!!

  3. #3
    Quote Originally Posted by Gunnery Sergeant Hartman View Post
    They are all for use in cold weather.

    What type of application are you looking for? Do yu live in Antarctica or something?
    I was under the impression that heat pumps do not work efficiently below 30-40 degrees F. That is why they are not used for the most part above the mason-dixon line. However, Hallowell's Acadia system does work super efficiently below freezing temperatures.

    I live in upstate NY not antarctica.

  4. #4
    Join Date
    Mar 2003
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    7,326
    I actually thought is was a good reply. There are many heatpumps that do well in "cold weather". The typical heatpump starts to lose capacity as the temps drop, but still work to a certain point. The reason for strip heat is to overcome that point where the heatpump can no longer keep up with the structures' heat loss, and to temper discharge air during defrost. Most of the minisplits do very well at low ambient with the inverter technology. Take a look at Daikin for example, They rate down to plus five I beleive.

  5. #5
    Join Date
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    Some of the minisplit manufactures do make what they call cold weather heat pumps which are effcient to lower temps than normal heat pumps.

    I am not sure off of the top of my head how low they can go but 0-5 seems to be what I heard. They are pretty pricey.
    Its a good Life!

  6. #6
    Join Date
    Sep 2006
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    1,253
    Mitsu does make a high heat output unit called the H2i in a 3 ton capacity. It is an inverter unit that has 100% of its rated heat output available down to 5* and 87% down to -4*.

    It only has two different indoor units that it can have mated to it, and only two can be connected to one outdoor unit.

    Here is the Mitus brochure: http://www.mehvac.com/UploadedFiles/...i_brochure.pdf See page six for the 3ton unit.

    Each of the Japanese manufactures (Sanyo, Daikin, Mitsu) have VRV/VRF systems that have very high heat output at their rated low temps. As an example the Daikin 4 ton unit is rated at 54,000 BTU heat output at 47* and with indoor units (four in this case) matched at 130% of the outdoor unit rated capacity it will produce 48,000 at 10* (my design temp). The system is rated to operate as low as 4*, but I hear they are run at lower temps without issues.

  7. #7
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    Quote Originally Posted by vandalay714 View Post
    I was under the impression that heat pumps do not work efficiently below 30-40 degrees F. That is why they are not used for the most part above the mason-dixon line. .
    Then you are under the wromg impression.

    I'm pretty sure we're above the mason-dixon line in PA.

    And heat pumps are used as much as any other type of heat sourse.

    Many of which have balance points between 20 and 25F before they need aux heat to assist with heating the home.

    And still provide heat down to -10F that cost less the just the strip heaters alone.

    Many of the mini split systems with inverters stop working at 14F. Some, go as low as 0F(they're consider to be low ambient).
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  8. #8
    Join Date
    Sep 2008
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    Vancouver, WA
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    Mitsubishi came out with two new mini split units that maintain their output at 17°.
    Here is a link to a press release.
    NEW MR. SLIM® HEAT PUMP SYSTEMS

    Hope this helps.

  9. #9
    Thanks for all the input guys! I have alot to research now. Thanks again.

  10. #10
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    Quote Originally Posted by beenthere View Post
    Many of which have balance points between 20 and 25°F before they need aux heat to assist with heating the home.
    This describes my situation perfectly in Baltimore, Maryland.

    Are you testing my heat pump in the winter when I'm not home?

    Take care.

  11. #11
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    Mar 2008
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    Jackson, NJ
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    Quote Originally Posted by beenthere View Post
    Then you are under the wromg impression.

    I'm pretty sure we're above the mason-dixon line in PA.

    And heat pumps are used as much as any other type of heat sourse.

    Many of which have balance points between 20 and 25F before they need aux heat to assist with heating the home.

    And still provide heat down to -10F that cost less the just the strip heaters alone.

    Many of the mini split systems with inverters stop working at 14F. Some, go as low as 0F(they're consider to be low ambient).
    Hey Beenthere, just out of interest what is your lockout temp? My guy did not do a analysis to get the balance point for my house. We set the lockout temp to 35 in the interest of avoiding the defrost cycle of my HP as much as possible. If I can put out enough heat at 30 and not defrost constantly, I'd move it down. Any thoughts?

  12. #12
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    I like to set the HP lock out at 20, and the furnace at 35. That gives a 15° overlap that both can be used(IAQ stat), and allows the home to take advantage of solar gain during the daytime.

    Not knowing the full performance of your HP, or the actual heatloss, I'd try 30°F, and see how that works.
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  13. #13
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    Quote Originally Posted by gary_g View Post
    This describes my situation perfectly in Baltimore, Maryland.

    Are you testing my heat pump in the winter when I'm not home?

    Take care.
    I pinged your stat and got its IP.
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