Well, they have electric boilers, gas boilers, and gas/heat pump hybrid boilers. but not restive/heat pump hybrids. (for houses heated with hot water) I suppose this is because the return temperature to the boiler is already 50 Celsius so the heat pump can’t help you at all
Edit: Oh actually, I was wrong.(and I guess it makes sense. It would suffer the same problems as an electric hybrid) There is no hybrid gas heat pump for hydronic heating. Basically my entire city is hydronic heating so heat pumps are not an option. However
a bunch of my neighbours have heat pumps and I suppose it’s just heating one room in their house and it’s not even connected to the thermostat of their hydronic heater in any way.. Seems pretty silly to me. At least you get an air conditioner out of the deal so that you can use more electricity in the summer.
There are air-to-water heat pumps that can run hydronic heating (even radiators, though underfloor is a better match due to the lower return temps).
You can then make your own hybrid with a resistive electric boiler or a gas boiler wired to second-stage or emergency heat.
My 1920s house with radiators and terrible insulation outside of Boston runs with return water temps in the low 90s in shoulder season and 120°F when it’s 12°F outside, using outdoor-reset/weather-compensation.
Those return temps are entirely compatible with air-to-water heat pumps. (And result in 22-24 hour run times per day, which makes for extremely comfortable heat, despite the generally lacking insulation.)
I don’t have one because HVAC contractors are living in the 1990s and want to do a 3-hour, 2-person combi boiler install for $10K in profit rather than think through how to do anything unusual.
