[PaulHoule]

What I've heard is the opposite. If you are going to burn fossil fuels for heat, those oil burning boilers are more efficient than most hot water heaters and furnaces. The hydronic system is also efficient at getting heat in the right place.

To really improve on an oil boiler, you could get a heat pump or maybe active or passive solar. If you have a system that generates hot water you could probably run it through existing pipes.

[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.