Heat pumps aren't meant to be turned on and off. In fact, they aren't meant to have the thermostat changed either, even at night. You set it to what you want an

Heat pumps aren't meant to be turned on and off. In fact, they aren't meant to have the thermostat changed either, even at night. You set it to what you want and it keeps it there. Once it gets the temp where you set it, it doesn't use much electricity to keep it there unless it is very cold, like below freezing and especially below -20C. Due to your high ceilings, it might be prudent to install ceiling fans to help circulate the heat, but I'm not a heating expert so I recommend asking one.