When does it make sense to temporarily set the thermostat back to save energy running a geothermal heat pump in the winter? I understand that it doesn't make sense to do so if you're away for only a short time--say, during the day while you're at work. But what if you're away for a weekend? For five days? For longer? I gather one reason setting the heat back then raising it can be less efficient than expected is because the heat pump will use its (inefficient) supplementary resistance heat coils to try to raise the temperature quickly. Is there a way to prevent this with most systems, assuming you don't mind it taking several hours to warm up using the heat pump alone? For background, this will be in a home used on-and-off for stretches of several days at a time; and it will have a Nest thermostat that can be controlled remotely. I'm interested in any thoughts, data, or guidelines professionals or experienced users might offer. Thanks.

There is usually a way to not engage the heat strips. With most air source heat pumps that is a function of the thermostat, but how that would work with a Nest on some unknown heat pump's controls it's hard to say.

Setting back to 50F is fine for a weekend or longer. With a Nest and an active Wi-Fi connection the recovery ramp can be started well in advance of your intended arrival time.

Appreciate the advice, thank you.

Appreciate the advice, thank you.

I googled "nest thermostat auxiliary heat strips" and got tons of answers.