Heat pump question

[Greg C.]

I have a 2017 38rl and my question is I know that the heat pump is only good down to about 40 degrees. If the outside temperature goes below 40 will it reach a point where the propane furnace will kick on and take over?

[mhs4771]

My understanding is YES. When turning on the Heat Pump, if you set the temp more than 3 or 4 degrees above the present temp the Gas will kick on to bring it up to temp than the Heat Pump should take over.

[NW Snowbirds]

My experience is that if the heat pump is running and the temperature drops below 40°, the heat pump will continue to put out cold air but the gas furnace will not start automatically. In my unit it is necessary to turn the thermostat back to the gas furnace at this point.

[Greg C.]

Thanks for answering my question. I knew that it would switch over if you were going higher but wasn’t sure about switching over if outside temps dropped below the temp that the heat put out warm air. That answers my question, thanks.

[RWJSIM2003]

Our 2015 38RL would swatch over automatic if the HP could not keep up even once the temp outside went below 38 degrees. Once the temp was about 4 degrees below the setting the Furnace would override the HP. Problem is that once the temp inside reaches the desired temp this process of HP then Furnace would start over again. It is best to set the furnace if you know that the Temps at night will fall below 40 and them switch back to HP during the day when temps are above 40.

[drj564]

Not that my post will help the OP but our 2018 39MB has the heat pump in the front bedroom ac unit. It does not control the furnace at all. It’s only AC or heat pump and will keep running regardless of outside temp. Ours is a 3 AC RV and the rear T-stat runs the rear AC and furnace. The living and kitchen are on the same duct AC wise only. The bedroom AC/heat pump only cools and heats the bedroom and front bath. The furnace however is 100% the whole RV. This setup is beneficial in that the heat pump can electrically heat the front and the fireplace can heat the rear. Then when it’s too cold the furnace heats the whole RV. 3 AC’s in the RV work really well in the summer. Just letting you know what they switched to in 2018.

[woodman1]

Originally Posted by NW Snowbirds

My experience is that if the heat pump is running and the temperature drops below 40°, the heat pump will continue to put out cold air but the gas furnace will not start automatically. In my unit it is necessary to turn the thermostat back to the gas furnace at this point.

In our 2017, once our two heat pumps can't keep up with the demand, the propane furnace ignites and you get forced air heat through the floor ducts. This has happened on a couple occasions recently when our outside temp went below 40.