On Wednesday, 21 August 2019 09:16:05 UTC+1, Chris Green wrote:
We want to put a 'dual fuel' towel rail in our new shower room.

Whatever, does anyone have any recommendations or "don't do it"
comments for particular brands or models?

I don't know what types your central heating or shower is, but I'm very happy with the "single fuel" towel radiators in my house. They are plumbed into the central heating primary side, before the diverter valve, such that they are heated whenever the boiler fires up, regardless of whether it's for heating the radiators or replenishing the hot water in the water storage cylinder.

So, for example, by the time we've finished a shower in the summer, the towel radiator has heated up to provide cosy warm towels, and to dry the towels again.

As I said, it works well for us. And there's no need for an electric element (which would need to be on a timer to heat up sufficiently in advance of you needing the radiator to be warm).