Results 1 to 9 of 9
  1. #1
    Join Date
    Nov 2006
    Posts
    15

    Heat Pump Design

    Anybody know of heat pumps working at low temperature wihtout having to go through defrost? By low temp I mean between 25-45 deg F.

  2. #2
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    66,764
    On an air to air unit. Only if you have no humidity in the outside air.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  3. #3
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    66,764
    I deleted your other thread, since its basically a duplicate of this thread.

    If you don't want a defrost cycle.
    Either set the heat pump to lock out before the outdoor temp gets cold enough.
    Or, get a geothermol heat pump installed.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  4. #4
    Join Date
    Nov 2006
    Posts
    15
    You know there is always some humidity. So, is there still a unit with no defrost at low temps 25-45F??

  5. #5
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    66,764
    Since I said only if there is NO humidity in the air.

    The answer would be no. For air to air heat pumps.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  6. #6
    Join Date
    Nov 2006
    Posts
    15
    What if using part of the discharge gas to run through an orifice and then attach it to the distributor intlet (after TXV, essentially putting hot gas back into the evaporator). This will raise the evaporator temperature and avoids less frost. Hav any body heard about this technique?

  7. #7
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    66,764
    Which would also mean you would get less heat from outside to put to the indoor coil. And have to run the more expensive aux heat to make up the difference.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  8. #8
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,389
    Look for a unit with "demand" defrost. At least they will defrost only as needed. A timer, which most use, defrosts constantly even with no frost.

  9. #9
    Join Date
    May 2009
    Posts
    196
    Quote Originally Posted by behmin View Post
    You know there is always some humidity. So, is there still a unit with no defrost at low temps 25-45F??
    What you're asking for is impossible for an air source heat pump. Defrost is required by the laws of physics.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event