Best way to heat a towel rail

[John Aston]

I plan to install a hot water towel rail. I'd prefer not to use an electric towel rail.

What's the best way of controlling the temperature of the towel rail? My criteria are (in order of importance):

1. Make sure it never gets hot enough for the kids to burn themselves (badly) should they touch it.
2. It should dry the towels and contribute to heating the bathroom in winter.
3. It should dry the towels in summer.

I was thinking of having an oversized towel rail running off one of the ports of my underfloor heating manifold. That way, the temperature of the rail will be warm 55 deg C and the large size will give it a reasonable output for winter heating. In the summer, I would turn the rail on/off with a timer, or perhaps it could be switched by the cylinder thermostat.

Does that sound OK? One disadvantage is that if the boiler flow is modulated according to the outside temperature, the temperature of the towel rail may fall below 55 deg C on warm days. (You could view this as glass half full rather than half empty, however.)

At what temperature would the towel rail be painfully hot to touch?

[MikeS]

Its better if you can connect the towel rail/rad across the boiler before the split between the hot water and heating circuit (like a bypass) on a low content boiler, this way you will get the towel rail heated in summer and winter and you can have a thermostatic valve on the rad if you like (preferred). You could run the pipe work in 10 mm plastic and thread it through the joists as you would ring main cable. I have mine across the flow and return before the diverter( sharing hot water and heating) valve and it works OK my diverter valves are in my airing cupboard in the bathroom so it was easy. MikeS

[Set Square]

Do you have your under floor heating on in summer? If not, and if you connect your towel rail to the UFH circuit, it ain't going to get hot. How is your hot water heated? If you have stored hot water, with primary circulation going through a coil in the HW cylinder, you could connect your towel rail into this circuit - which would be fine for summer, but would only get hot when the HW was actually being heated, even in winter.

As someone else has suggested, you *could* connect it into the primary circuit on the boiler side of any zone valves - then it would get hot whenever the boiler is running - either for HW or UFH or both.

As far as surface temperature is concerned, most people manage not to burn themselves on radiators running at 80 degrees or more, so I wouldn't worry too much. Obviously, you don't want to cop hold of anything at that temperature for any length of time, but a quick touch won't hurt you.

[John Aston]

I was planning on controlling it so that all valves on the manifold, except the towel rail valve, would be off in the summer.

Right, so I would need to install extra heating in the bathroom for winter, which I'd prefer not to do.

Wow! 80 degrees sounds hot. I wonder if there's any regulatory guidance on this.

[John Aston]

Mike, is that thermostatic valve a room temperature valve or does it control the surface temperature of the towel rail?

[MikeS]

No it controls the room temperature by reducing the flow through the radiator, as the temperature rises above the temperature set by the thermostatic radiator valve. So whilst getting the room to the temperature set by the thermostatic valve the radiator can get as hot as the boiler water temperature. Normally a surface temperature of over 140 F can burn so its better to use an enclosed radiator if young children are about. Otherwise don't let your bum touch a hot rad in the bathroom. Most people manage not to burn themselves on the bathroom radiator or at least they only do it once.

MikeS

[John Aston]

I've since found that Danfoss do a return temperature limiting valve type FJVR (it costs about £15). It controls the flow of the water through the towel rail until the temperature of the water is close to the value set on the valve thermostat. The towel rail is kept at a safe temperature, regardless of room temperature.

I could combine this with your suggestion of connecting the towel rail circuit into the primary circuit on the boiler side of any zone valves. This way the towel rail will get warm when the hot water is on (in Summer and Winter) and the when the heating is on in Winter. The temperature of the rail will never go higher than its thermostat setting.