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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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New Honnywell RTH63D installed Original not available bought

Customer Question

New Honnywell RTH63D installed Original not available bought house as a foreclosure. Heil Heat pump and gas furnace run at same time.
Submitted: 2 years ago.
Category: HVAC
Expert:  Phil replied 2 years ago.


So far it sounds like a thermostat wiring error, unless that same thermostat worked properly earlier, in that case it may have gone bad.

Tell me a lot about your technical skills background so that I can coach you most effectively.

Meantime if you can send me a clear well lit, well focused, close up photo of the wiring diagram glued to the inside of the blower cabinet door, and a photo of the printed circuit card where the thermostat wires attach I can mark those up with trouble shooting instructions.


Customer: replied 2 years ago.
I was a Master auto Tech for 14 years so I can handle a meter and tools. The English language, well that's another story. I am starting to think the thermostat is not the correct one. Perhaps it does not sense a quick enough change in temp and calls for W2/AUX-E thus firing the gas furnace with the HP still running. (The Thermostat box states works with heat pumps however). Removing the white wire from the thermostat W2/AUX-E and set thermostat to call for heat = HP comes on and produces 102 degrees at duct with an 45 degree outside temp, not to shabby. Of course the gas furnace did not come on because of white wire removed from thermostat. After messing with this it appears that if inside temp is 2 degrees apart from what the setting is calling for Emergency Heat i.e. AUX-E is activated. You can even hear a click sound from the thermostat. So i am thinking now wrong thermostat. Your thoughts. If you agree after review what thermostat would be correct to purchase. Clearly this unit did not have fancy indoor outdoor temp sensors before. (this was a foreclosure so more than likely not the original thermostat) Another handy piece of info. The AC side of the HP was not cool in the start of summer. I put my gauges on and system was low. I checked for leaks with electronic sniffer (for autos, but cfc is cfc) no leaks found. Had system charged AC work fine all summer. Now I presume the system was low because the HP and Gas Furnace ran at same time previous winter thus causing an over pressure in the system and loss of refrigerant.
Expert:  Phil replied 2 years ago.

Hello again, regarding your english at least in writing it is better than perfect, it is very very good.

If your speech is not as good you are probably just missing a few sounds that are alien to your native language. You could ask a co-worker to tell you what those sounds are and then coach you on getting those right... they will feel very unnatural to you no doubt and without the mouth and throat muscle memory to do them, but it can be done if you focus on just one of these odd sounds at a time, break the sound down into just parts of the sound, not even the whole sound. Maybe just how the sound first starts... practice that.


You wired the thermostat for a conventional system, not a heat pump, that is the problem. move all the wires straight down color for color, including the R to Rc jumper.

That should work, if you get heating when the thermostat is set on cooling, we may have to swap the orange wire for the unused blue wire, OR... go into the thermostat programming and reverse the action of the O/B connection.

We can go from there.

Customer: replied 2 years ago.
It is wired color for color to the symbols below the terminals. Exception, white wire is attached to Aux/E, there is no W symbol. See attached photo. If the white wire is removed no gas furnace operation and HP runs producing heat fine and dandy. If White wire is attached to Aux/E terminal and the system calls for emergency heat the gas furnace (white wire) is energized and the HP will still run at same time. Not Good.This is the problem. Why does thermostat keep HP on when gas furnace is energized.
Expert:  Phil replied 2 years ago.

Attach the white wire to Aux/E.. that runs the furnace as back up to the heat pump.... aux/E is only energized through the Red wire when the thermostat is set more than 3 or 4 degrees above the room temperature, look at the thermostat programming to adjust that.