heat pump switching to cooling during heat cycle

Reply

  #1  
Old 11-16-08, 11:53 AM
B
Member
Thread Starter
Join Date: Nov 2008
Location: birmingham
Posts: 3
Received 0 Votes on 0 Posts
heat pump switching to cooling during heat cycle

I have a coleman heat pump that is 20+ years old. It starts up its heating cycle normally in that the condenser, compressor, and air handler come on simultaneously. The piping going into the air handler from the heat pump is hot and the air into the house is warm. BUT - Halfway through the cycle you can hear a valve actuate in the heat pump. The condenser fan turns off and the piping going into the air handler becomes very cold.
could the reversing valve be switching? What would cause that?
Heat pump s/n-118478436
mod-3024-911
Air handler s/n-098564157
mod-3600-840
 
  #2  
Old 11-16-08, 06:36 PM
airman.1994's Avatar
Member
Join Date: Dec 2005
Location: VA
Posts: 5,795
Received 8 Votes on 8 Posts
Its doing what it is supposed to do by going into defrost.
 
  #3  
Old 11-16-08, 07:26 PM
B
Member
Thread Starter
Join Date: Nov 2008
Location: birmingham
Posts: 3
Received 0 Votes on 0 Posts
problem is... the unit never is able to satisfy the thermostat because of the constant change in the temperature of incoming air. The heat pump runs constantly. i have had a technician look at it and he said that it was performing normally. it just doesn't seem very efficient to blow COLD air into the house when i am trying to raise the temperature.
 
  #4  
Old 11-16-08, 08:30 PM
D
Member
Join Date: Jan 2008
Posts: 49
Received 0 Votes on 0 Posts
>>it just doesn't seem very efficient to blow COLD air into the house when i am trying to raise the temperature.

Its not efficient, but the alternative is that your heat pump will turn into a solid block of ice and die. Some of the newer models use temperature sensors on the coils to know when to reverse to defrost. Others, particularly older models, just use a timer and reverse every 30,60, or 90 minutes whether it needs to or not.

Your heat pump is old. (I hope mine lasts that long.) It really owes you nothing at this point. You might want to consider a new one which would be WAY more efficient. A new heat pump will still reverse to defrost, but most likely less often and will put out more BTUs in the meanwhile so you can reach your set temp on your tstat.

-Doug
 
  #5  
Old 11-17-08, 06:44 AM
D
Member
Join Date: Sep 2008
Location: NY
Posts: 433
Received 0 Votes on 0 Posts
What is your auxiliary heat source (aka em heat): furnace, heat strips?

Defrost is normal but your aux heat should be coming on during defrost cycle to temper the air. Otherwise, as you've noticed, it is hard to satisfy the tstat when defrost comes on.

Do you feel warm air still blowing out of the registers during defrost?
 
  #6  
Old 11-17-08, 07:38 AM
B
Member
Join Date: Aug 2007
Location: Northwest Arkansas
Posts: 20
Received 0 Votes on 0 Posts
Originally Posted by brewboy50 View Post
problem is... the unit never is able to satisfy the thermostat because of the constant change in the temperature of incoming air. The heat pump runs constantly. i have had a technician look at it and he said that it was performing normally. it just doesn't seem very efficient to blow COLD air into the house when i am trying to raise the temperature.
If the unit runs constantly as you claim, and your in Birmingham,Al, you might very well have a problem. Have a tech replace your defrost board as it sounds to me that it isn't coming out of defrost mode properly or is cycling into defrost mode too often.
 
  #7  
Old 11-17-08, 07:43 AM
D
Member
Join Date: Sep 2008
Location: NY
Posts: 433
Received 0 Votes on 0 Posts
Originally Posted by Bigbooty View Post
If the unit runs constantly as you claim, and your in Birmingham,Al, you might very well have a problem. Have a tech replace your defrost board as it sounds to me that it isn't coming out of defrost mode properly or is cycling into defrost mode too often.
Yes, that is a good point. At about what temps are you seeing defrost, how often does it happen, and how long does the defrost cycle last?
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: