[ianburrell]

Geothermal heat pumps are more efficient. They also ignore air temp so they keep working efficiently when cold outside.

The downside is that geothermal is expensive and hard to retrofit. They make the most sense in new construction in cold climates or adding to large properties.

[belorn]

Geothermal heat pumps can work great in retrofitting old system with a water heater. My family house is over 100 year old and the original water heater used coal in 1920, then it was changed to electrical around 1980s, and is now fitted with geothermal heat pumps. Geothermal was installed as a cost saving measure and cut down the heating bill by more than half. All the old cast iron radiators are still the original ones.

[fifilura]

Yeah, best deal if you already have water based central heating and radiators. Which is pretty common here in Sweden since don't really have air/gas heating systems, so our houses are not built with air ducts.

Better efficiency (you use maybe 30% of the electricity), connects to the central heating so it supports the entire house.

I installed mine for $15k but that was 20 years ago and included subsidies.