How to make a dual fuel towel radiator work?

[Mr Punter]

I have got dual fuel towel radiators that are on the central heating radiator circuit and have an electric element with fancy electronic control.  I don't really want to use the central heating bit, so for electric, should I close both the valves, or will this potentially cause a problem with hot water expanding?

[A_L]

Why not just close one valve? This assumes this is not a 'bypass' radiator.

Water expands by about 3.5% over the range 20°C/70°C

https://www.engineeringtoolbox.com/volumetric-temperature-expansion-d_315.html

Edit - forget this 'idea' Or leave enough air in radiator to absorb this without significant pressure increase, assuming this does not affect thermosyphon/circulation within radiator.

 

Edited September 25, 2018 by A_L
As itallic text

[Mr Punter]

OK one valve makes sense. Thanks.

[NSS]

Our towel rads are on loops from the UFH circuits but also have electric elements. We leave both valves open all year round and seem to suffer very little 'leakage' of heat into the UFH when using the electric elements.