[brudgers]

Most places with boilers are too cold for air to air heat pumps to be viable during heating season. Geo-thermal heat pumps have a wider range but they involve significant site work and require a non-trivial lot size. In terms of expense a typical geothermal heat pump will have a very long payback period. An open loop geothermal heat pump might be practical if there’s a source and sink for the water running through it. Most people don’t have those. But it’s a simple system with a water pump and fan as the only moving parts.

[toomuchtodo]

Air source heat pumps can operate all the way down to 0F. I’ve paired one with a hydronic system, with a firewood heated boiler for backup heat, in rural Pennsylvania.

The less reliable power is and the colder it gets during winter months, the more tricky the problem gets.

[brudgers]

Typical residential units come with a resistance electrical heating element. It forms the basis of the "emergency heat" functionality. It also begins operating as ambient outdoor conditions exceed the performance of the heat pump mechanism.

I mention this not because this is what your particular system does. I mention it because it is typical for widely available residential heat pumps in the ordinary market.

[PaulHoule]

Yep. The real selling points of heat pumps is comfort, since they can go from aircon to heat and back seamlessly. Where I live geothermal heat pumps are the practical option, but south of Pennsylvania the air source heat pumps are a great option.

[brudgers]

To me, they are a no brainer in the Florida peninsula. Above that, I'd start to consider a furnace and an air conditioner as an alternative for better heating aesthetics (quieter and warmer air at the register). Also, sizing the AC properly to prevent short cycling, means a heat pump will not heat as quickly a furnace. With a furnace, short cycling is not an issue.