I have a heating system with both a heat pump and a boiler. The rule for the system is that if the temperature in a zone is 5° F less than called for, then the boiler will come on, but otherwise the heat pump will try to heat the zone by itself.
The problem with this is that I can't get one of the zones to 72° F. What happens is that it is cold outside, so the heat pump can only get the temperature to 70° F and it stays there. If I increase the called for temperature in the zone to be 75° F then of course the boiler will come on, but it would raise the temperature to 75° F which is too hot.
How do I solve this problem?