Originally Posted by Bartek
Can anyone explain what the “heat pump” thermostat setting does comparing to the “furnace” setting?
In modern Airstreams the A/C is also a heat pump. Basically it runs the opposite of cool. It takes heat out of the air and sends it to your vents. If you're plugged in and paying for power, it makes sense to use the heat pump. On furnace, you're using your propane for heat.
The downside of the heat pump is it doesn't work very well below 35 deg. So our smart thermostats have a secret program that at a predetermined temperature, switches from heat pump to furnace.
Heat pump air exits at the ceiling, while furnace heat exits at the floor making for toasty feet in the morning. In either case, I'd run a fan to move air around.
You will notice with the HP that the condensate will run off the roof and not down the drain tubes like with cool. It's all because the unit is running in "reverse".