[jacobush]

Reading from the other side of the pond, heating and electricity in the US seems so fantastically complicated. Where I live, the standard is water radiators for old installations and new. The last 20-30 years or so each radiator has a thermostat. (Bimetal, no electronics.)

That's it.

Somewhere there is a reservoir and something to heat the water. It can be anything, and indeed most older homes have been converted a few times already but nothing changed in the water system itsef. (For a house to have started with a wood furnace, then oil, then electric, then municipial heating or solar or whatever, is completely normal.)

The water either circulates by convection (very old systems), or with a pump. If the pump fails, convection typically still works, just less flow.

[beerandt]

If you only need heat, it's a lot less complicated.

But even chilled water systems start to get complicated because of humidity and condensation.

And if you're already installing a forced air HVAC system for the 'AC' part, then installing radiators for heat is usually superfluous.