Heat pump won't work in heating mode


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Old 10-14-06, 09:16 AM
J
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Heat pump won't work in heating mode

Hello -

I have a 3-ton Lennox heat pump that will not work in heating mode but will work in cooling mode. I also have an auxillary Lennox LP gas furnace as a backup. When I turn the thermostat to heating mode the outside heat pump will not turn on. However, the basement gas furnace will cut on and produce heat. I think the problem might be a faulty thermostat. Ever since I moved into this house the thermostat hasn't seemed right especially in heating mode. The mechanism in the thermostate that controls the heat pump would hesitate for 20-30 seconds before the heat would kick on. Now I'm wondering if it has failed completely. Thanks for any info you can provide.
 
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Old 10-16-06, 11:01 PM
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Have you checked if you have a outdoor tstat? most unit with gas back up have one that will say if the HP will come on or the gas furnace will.

ED
 
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Old 10-17-06, 07:54 AM
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Originally Posted by Ed Imeduc
Have you checked if you have a outdoor tstat? most unit with gas back up have one that will say if the HP will come on or the gas furnace will.

ED
I did some further troubleshooting and this is what's happening. For example, say the temperature is 65 degress on the first floor and I turn the heat on and select a desired temp of 75 degrees. The gas furnace will run until the temp in the room is 75. If the room temp drops below 75, the outside HP will start up and heat the room from then on. So my guess is that for rapid warm ups where the current and desired temp is greater than 5 degrees the gas furnace (backup heat) will be used to heat the space. For maintaining the temp , the outside unit will run if it's over 32 degrees outside. Is this a logical explanation as to what might be happening.



Where would the outside thermostat be located and what does it look like? My understanding is that once the outside temp drops below 32 deg the gas furnace will run exclusively.
 
 

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