I have a Runtal, too, and it heats the entire small bathroom in addition
to warming towels, so we shut off the forced air vent in that room.

They also have models that hook into hot water heating systems, which I
think the OP said they have.

I first came across these at a ski resort in Switzerland where they not
only heated your room, but dried and warmed your clothes. They are not
cheap, but if you want quality you have to pay the price.

Patrick wrote:
Bought a Runtal electric model (direct wire, with programmable
console) fairly expensive (-around $800) But is the best gadget I ever
got. If it went out I would order a new one immediately. (7 yrs old
now) An unwarmed towel feels cold and like it is already wet. I tried
a couple of the freestanding models which were crap.It is well worth
it, in my opinion.