Possible Heat Pump Problem


  #1  
Old 03-05-07, 10:50 AM
N
Member
Thread Starter
Join Date: Mar 2007
Location: United States
Posts: 8
Likes: 0
Received 0 Likes on 0 Posts
Possible Heat Pump Problem

Here within the last few months my heat pump has been acting strange. Back in December I had an usually high electric bill, so I stated monitoring my electric usuage and noticed that my heat pump would run constantly. I had a service tech come out, and he found a problem with the expansion valve. (I may be wrong on the proper term for the valve, but basically it controls the Freon flow coming into the furnace through the large copper pipe). That explained the high electric bill for December, basically the Aux Heat was heating the house, plus the compressor would continually run. Now here recently I have noticed (after an even high electrical bill) that the Heat Pump runs non-stop, even after the temperature set point has been reached. After watching the t-stat closely the heat pump runs non-stop (set point has been reached), then the Aux Heat will come on for a few minutes, then go off, but the heat pump continues to run. Set point or current ambient temperature does not changed. After noticing this I call the service tech again, and explain my problem. He came out and measured the air coming from the vents, Set point = 73F, Air Temp = 89F (Heat Pump Only). When Aux turns on the Air Temp rises to around 119F. He said it appear that the heat pump was working correctly, but thought maybe the t-stat was bad since Aux was coming on even after the set point had been reached. He changed out the t-stat, and it appeared to be working correctly for a few hours, but now I am noticing the same pattern (Heat Pump Runs non-stop even after set point is reached, then from time to time the Aux Heat kicks on). Is this normal? I have been in the house for 4 years now and have never noticed it doing this, plus my electrical bills are double what they were last year this time. I am at work right now so I don't have the specs on the heat pump, but it is an American Standard (not sure of exact size right now, but can provide that if needed).

Thanks,
Steve
 
  #2  
Old 03-05-07, 08:22 PM
M
mjb
mjb is offline
Member
Join Date: Dec 2006
Location: NC
Posts: 78
Likes: 0
Received 0 Likes on 0 Posts
Call that tech back and have him check the thermostat wiring connections. It really sounds like a thermostat issue. Let us know how it all works out. Better yet, call another Hvac contractor. It appears that this service tech is just throwing parts at the problem.
 
  #3  
Old 03-05-07, 08:32 PM
Ed Imeduc's Avatar
Member
Join Date: Aug 2002
Location: Mountain Williams Missouri
Posts: 18,386
Likes: 0
Received 1 Like on 1 Post
Wink

Id wonder about the freon charge there now if he put in a new TXV valve on it. Is the big copper line hot at the unit inside??
 
  #4  
Old 03-05-07, 09:37 PM
A
Member
Join Date: Feb 2007
Location: Goodyear
Posts: 73
Likes: 0
Received 0 Likes on 0 Posts
Cool

I actually agree with ed. I would look at the units charge. It seems to be trying to work. Can you check the temp. at the supply and return vents? This can help figure if the heatpump is putting out any heat. In a 4 year old house you could have a slow leak. BUT this should have been caught if he replaced the TXV.
 
  #5  
Old 03-06-07, 10:03 AM
N
Member
Thread Starter
Join Date: Mar 2007
Location: United States
Posts: 8
Likes: 0
Received 0 Likes on 0 Posts
Thanks for the feedback. The last time the service tech came out I did ask him to check the charge. He checked it and told me it was within the normal range. The large copper pipe coming into the furnance does get hot to the touch when the heat pump is running. I can check the temperature at the supply and return vents tonight (and post) when I get home. As for the thermostate wiring, could something at the compressor or at the furnance become disconnect that could cause this problem?

Another question that I have is should Aux Heat come on with the Heat Pump even when the temperature setpoint has been reached? I don't think this normal, but I do see this happening daily (even when outside temp is > 30F)

Thanks again,
Steve
 
  #6  
Old 03-06-07, 10:07 AM
mattison's Avatar
Member
Join Date: Mar 2003
Location: Cinti, OH
Posts: 5,547
Likes: 0
Received 0 Likes on 0 Posts
If you turn it off at the t-stat does the outside section continue to run ?? If so then the contactor is stuck closed.
 
  #7  
Old 03-06-07, 10:17 AM
N
Member
Thread Starter
Join Date: Mar 2007
Location: United States
Posts: 8
Likes: 0
Received 0 Likes on 0 Posts
Mattison..Yes to my knowledge every time I turn the unit off or switch to emergency heat at the t-stat the compressor shuts off.
 
  #8  
Old 03-06-07, 07:02 PM
N
Member
Thread Starter
Join Date: Mar 2007
Location: United States
Posts: 8
Likes: 0
Received 0 Likes on 0 Posts
Ok, got home tonight and took the following measurements.

T-stat set point = 71F
Vent Temps = 89F (stage 1)
Return at furnace just above filter = 71F
Return Vent First Floor = 75F
Return Vent Second Floor = 71F
Outdoor Temp = 29F

Heat pump continues to run, and aux heat kicking on and off every 15 minutes or so.

Thanks for your help!
Steve
 
  #9  
Old 03-06-07, 08:11 PM
A
Member
Join Date: Feb 2007
Location: Goodyear
Posts: 73
Likes: 0
Received 0 Likes on 0 Posts
Cool

Thats a 18 degree split - not bad for a heat pump

how are your r factors - wall and ceiling
can you keep the heat in is what i'm getting to...
is it shutting off when you reach set point?
 
  #10  
Old 03-06-07, 08:55 PM
M
mjb
mjb is offline
Member
Join Date: Dec 2006
Location: NC
Posts: 78
Likes: 0
Received 0 Likes on 0 Posts
Have the tech check or change out that thermostat. Why else would the auxillary heat strips cycle every 15 minutes? According to your OP the supply temperature is normal with heat pump only operation. I had a similar problem with a Honeywell thermostat and promptly returned it. I eventually went with a Robert Shaw thermostat and have had no problems since.
 
  #11  
Old 03-07-07, 05:24 AM
N
Member
Thread Starter
Join Date: Mar 2007
Location: United States
Posts: 8
Likes: 0
Received 0 Likes on 0 Posts
I am kind of leaning toward this being a thermostat issue also, but since this is the second thermostat that has had the same issue I want to be sure that is what it is before I replace it. The old and current thermostat are both Honeywells. I am not sure what R factor insulation was used in the walls and ceiling, I could go back and dig that information up if needed. The house was built 4 years ago, and seems to be well insulated. When I went to bed last night the heat pump was running, set point of 71 had already been reached. I got up a few times through the night and never noticed the heat pump off, I think it ran all night. Any other ideas?

Thanks
Steve
 
  #12  
Old 03-07-07, 07:16 AM
A
Member
Join Date: Feb 2007
Location: Goodyear
Posts: 73
Likes: 0
Received 0 Likes on 0 Posts
Talking

buy a new house?
 
 

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