[LEAKYSEALS951]

Mine is about 91-92.

The heat pump works like this- with switches- cool- off- heat- emergency heat.
In the heating mode, the heat pump runs, but will auto kick over to propane when the temps get low. What specific temp that is, I don't know.

Emergency heat mode just bypasses the heat pump and runs straight propane.

I can always tell when the heat pump switches to propane, as the heat coming out of the vents will be warm, and will actually warm the floors, compared to the "cool drafty" feeling of the heat pump. I don't know what temp the device kicks over. I can also pull an upper cover off the indoor furnace itself, and you can feel/see the blue flames.

Perhaps at low temps, reverting to EH just reduces wear and tear on the heat pump, but when it's really cold, say 10- 20 degrees, I don't hear the outdoor unit cycling on / off. It does seem to cycle when it's in the 40-s- 50's, when it actually could be extracting heat from the great outdoors.