Cold Air When Heating....verification that diagnosis is true.


Old 01-24-05, 08:19 AM
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Cold Air When Heating....verification that diagnosis is true.

The post may be lengthy so I apologize, but I want to give adequate background.

We had a heatpump that was present when we moved in at 1998. It appeared to be installed in 1991. The first year we moved in we noticed that the heat was adequate. Not the best mind you, but I had heard that heat pumps never feel hot for heat. The next year when the heat when on I noticed that the pump was freezing up or basically having a lot of frost on it. The previous year when this happened it seemed to cycle to defrost it off and so on. I attributed this freezing up due to the fact the temperature was unusually cold as it was near 10 degrees. I ran the emergency heat which cost me a lot later. I don't remember though if the defrost was kicking in or not. In any case, I thought it wise to call an heating/air specialist. They basically checked the unit out and said it was fine and that when it below 35 degrees heat pumps don't heat that well or not as hot. Well we had a new baby the highest the temp was getting without the heat strips on was 62. So I ran the heat strips instead. Much hotter, but wow my electric bill was out the roof. Something like 400.00 for my 320 square ft house.

After my big bill I looked at a way to lower the costs. A friend told me he had gas heat and that it worked great. At the time gas was not that expensive. So I talked with the same heating people who earlier had come out to look at the unit and they installed a gas furnace for me. I went with a recommended option of getting a dual system. One where the heat pump was used until a certain threshold and then the gas would kick in. Right after they installed it and it was cold I switched on the heat. Well instead of the heat pump and then gas order the unit just tripped a circuit breaker. The heat guys came back out and determined it was because both the heat pump and the gas wer trying to kick in. They installed a relay to alleviate the issue.

When the next winter came we tried the dual, but again the heat pump seemed cold so I just flipped it to the gas. We did this same thing the following two years or so. This year when it was cool out, but not really cold I decided to have the heat pump run and use the normal dual method. Again the air was cold and eventually the gas furnace kicked in each time. I called the heating company that installed the furnace and the dual adapter. The technician came out and looked at it. He was kind of puzzled as to what was wrong because said though it was on heat the heat pump was stuck in cooling mode. He checked the freon and so on. Eventually another technician from the company came out and after looking it over and such felt that the problem was the reversing valve. Basically it was stuck in cool mode. Unfortunately the unit was out of warranty and to fix it would cost 900.00 or so. They recommended that instead of doing that I should consider another unit.

Well I was concerned that they may be wrong so I got another technician from another company. I did not tell him anything about already having it looked at or what the previous people said. He checked the freon, looked at the comrpession valves, etc. Eventually he said the samething that the reversing valve was stuck. He like the first company recommended instead of fixing it that I get another unit. However, unlike the first he said that in his opinion I should wait until the unit completely went out. Since it was stuck in cool and it the compressor and such was fine he recommended that I just do what I had been doing which was use the furnace for heat and then just use the heat pump for cooling. When it went completely out then I should look at replacing the entire outside unit (not the furnace inside). I was fine with this because though a little more the gas has been great. My bills in the really cold months was much lower than when I had those heat strips going.

Anyway, I wanted to post here to see if what both companies said falls in line with what the problem is. What I have wondered is if it could be something else. I have read things online where the reversing valve can be stuck in one mode because the signal it receives is just for the one mode. Something like the defrost unit is stuck in defrost mode or something. I have also wondered if with the dual setup or the relay installed that they could be sending the wrong signal. That even when in heat it still sends a cooling signal. I guess I just want to know what the other possible problems are before I resolve to leave as is and just use the heat pump for the air in the summer and the furnace in the winter. Any suggestions and instructions on things I can check for would be greatly appreciated.

Oh, one other question. I read somewhere that if the reversing valve becomes stuck there are some crude ways to try to unstick it. Stuff like switching heat and cool back and forth ro even hitting the valve with a hammer. Does this stuff really work?

I added this later, the heat pump and the furnace are Lennox brand btw.
Old 01-24-05, 08:44 AM
Ed Imeduc's Avatar
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Its very hard to say yes or no when you cant check the unit out yourself. So about all is kick it around.

The technician came out and looked at it. He was kind of puzzled as to what was wrong because said though it was on heat the heat pump was stuck in cooling mode. He checked the freon and so on. Eventually another technician from the company came out and after looking it over and such felt that the problem was the reversing valve. Basically it was stuck in cool mode.
????? Did he tap on it?? 1991 the valve should fail in heat would it go to heat and then cool when he tried?? can it just be the coil is bad on the reversing valve.
Then on this set up most have an outdoor tstat that will turn the heatpump off and the gas furnace on. Can that have the valve on cool??? Yes can be the defrost board. When you go from heat to cool and back is there a shhusss sound there at the valve
I would say you can have a lot of IFS IFS here for sure. Each one you have to prove out .
$400.00 for 320sq ft???????
to compare fuel cost for where you are go

Old 01-24-05, 09:28 AM
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I don't know if he tapped on it. All I know is that when switch to heat it was still stuck in cool (which from what I read on different places was unusual). The relay and the adapter for the heatpump/gas furnace deal is inside the house, in the crawlspace near the unit. As for the shhusss sound, I don't know, but the heat guys did not seem to indicate it did. All they indicated was that despite the heat being turned on, the unit was stuck in cool mode which they attributted to the valve.

I don't mind getting a third opinion. Should I? Should I ask them specific questions then about the defrost, relays, etc.? Could I do the tapping on the valve myself and if so how should I do it? How should I listen for the shhuss sound? If when switching heat to air and vice-versa even if stuck should I still be hearing it? What coil for the valve do you mean? Something inside the valve?

Yes the 400.00 dollars was with the old heat strips several yeas ago. They are no longer present. Now with electrical and gas heat I am looking at about 170.00 a month or so for heating the house during the really cold months (2-3 months) which does not see that bad to me. I tend to think if we replaced the single pane aluminum windows we have I would save a lot more.

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