Furnace turns on when only the AC/Heat was activated

[rruppert]

I have a brand new 2021 FR3 and I had air conditioner heat turned on. The AC united started and blew heat for some part of the night. During the night the furnace automatically turned on. I did not activate the furnace on my thermostat and would have rather used the AC heat all night rather than my propane. Is there something wrong or is this just a feature of the AC/Furnace/thermostat that when the temperature drops below a certain minimum, the furnace activates? I did not actually check the furnace (by opening it up and looking for a flame) and the blower could have been the only item activated, is that possible?

[DougW]

Mine does the same thing if there is a big difference between the set temperature and the room temperature. I think it is a feature but have not seen any documentation to support that.

I just pull the 12V fuse for the furnace if it bothers me and run the heat on electric and set the fireplace to come at a couple of degrees below what the thermostat on the wall is set to.

[bubbles]

Originally Posted by rruppert

I have a brand new 2021 FR3 and I had air conditioner heat turned on. The AC united started and blew heat for some part of the night. During the night the furnace automatically turned on. I did not activate the furnace on my thermostat and would have rather used the AC heat all night rather than my propane. Is there something wrong or is this just a feature of the AC/Furnace/thermostat that when the temperature drops below a certain minimum, the furnace activates? I did not actually check the furnace (by opening it up and looking for a flame) and the blower could have been the only item activated, is that possible?

This may be applicable to your heat pump operation:

Auxiliary Heat (Heat Pump Models Only)
Auxiliary heat operation will be activated when the measured temperature of the outdoor temperature sensor is less than 30 °F (-1 °C). If the system is equipped with a furnace, the control will select FURN heating mode for the auxiliary heat source. Auxiliary heat operation, once initiated, will have priority over a heat pump defrost cycle. Auxiliary heat operation will be de-activated and the heat pump operation will resume when the temperature of the outdoor temperature sensor is higher than 35 °F (2 °C).

[rruppert]

Thanks for the info/comments. Next time I am out with the heat on, I will check to see if the furnace actually ignites or if it is just the fan blowing.

[NXR]

Originally Posted by rruppert

Thanks for the info/comments. Next time I am out with the heat on, I will check to see if the furnace actually ignites or if it is just the fan blowing.

If you have the Atwood AirCommand unit like the GT5 does, the heat pump shuts down at roughly 45 degrees, not 30. When the heat pump automatically shuts down, the propane furnace automatically fires up.

Ray

[rruppert]

Hey Ray,

Yes, we have the Atwood unit. That sounds a little closer to what was happening. Around 45 degrees the Atwood heat pump would turn off the the furnace blower would start up.

And Vice-Versa, when it got above 45 degrees, the furnace blower would stop and the Atwood heat pump would kick on again.

Robert

[RobbieH]

Our Monaco Class A did the same thing, heat pumps on the rooftop would work up to a certain low point, then it would switch to furnace. Lucky for us, that meant our Aqua Hot and not our propane.

[bubbles]

Originally Posted by rruppert

Hey Ray,

Yes, we have the Atwood unit. That sounds a little closer to what was happening. Around 45 degrees the Atwood heat pump would turn off the the furnace blower would start up.

And Vice-Versa, when it got above 45 degrees, the furnace blower would stop and the Atwood heat pump would kick on again.

If you would have posted this to start with Paul the answer would just have been "normal operation".

[Big bird]

You have an upgrade unit. When you reach the capacity of the AC/HP, it automatically turns on the furnace.