I got one put in my bathroom last year:
– fluid filled towel rail as a part of the central heating system. CH comes on, towel rail gets warm.
– electric element added
– electric controller added. This allows me to set a program (24h/7 day programs are available) but I only really use it to do a 1 hour boost, to get towels dry if I know the CH isn’t going to come on.
– a towel rail isn’t as good at putting heat in to the room than a proper radiator, so you may need a bigger towel rail than you have radiator.
– a bigger towel rail can dry more towels…