Heat pump question.

[Zero Knievel]

At what temperature will the auxiliary heat kick in?  I know that an A/C will struggle to cool once it’s X hot outside because it’s harder to discharge the thermal energy into the air, and likewise, a heat pump will struggle once it’s cold enough outside that there’s insufficient thermal energy to draw from the air.

 

It’s in the low 20s.  I didn’t turn up the gas heat, and I see no indication that the auxiliary heat came on.  Thermostat was set to 69 degrees.  It is a dry cold as compared to a damp cold.  I’ve only seen the auxiliary heat indicator come on when trying to bump up the temperature by several degrees in on jump.  If I go from 69 to 70 then from 70 to 71, it doesn’t kick in.

[JoWhee]

Unless it's a new superefficient unit you should be on Aux heat at 20 degrees. If you're getting heat don't worry about it. I;m not going to explain the parameters for when the AUX heat comes on, I'm sure there are more than a few long and boring articles about it via google. 

[superhawk996]

On 1/23/2022 at 3:37 AM, Zero Knievel said:

At what temperature will the auxiliary heat kick in?

When the unit decides that it's needed.