Radiator heats up at frost setting

[Gizasmum]

Hi, wondering if anyone can help clarify why the radiator in my bedroom, which is set at the frost setting, still heats up when my CH is on. It is located on an internal wall, in a room that is rarely cold, and I have only just noticed this is happening. I thought that it being on frost setting meant that it would not heat up unless the frost temperature setting was reached.

I removed the valve cover (the bit with the numbers on it) and the pin was stuck in the valve, so I sprayed some WD40 on it and this loosened it. However this has made no difference re the radiator still heating up on frost setting.

I want to check I am not missing something obvious before calling out British Gas, as I am covered by their plan. Helpful words in plain English would be much appreciated as I am not in any way DIY minded. Thanks for your help.

 

[seco services]

Could be the wax capsule in the head is knackered if its this type.
Try another head off one of the other rads.

 

[Gizasmum]

Thanks, I'll try that tomorrow morning and post result

 

[Gizasmum]

I switched the valve caps over and my bedroom radiator works properly now and the other cap doesn't. Didn't think to do something like that, doh! So all I need to do now is get a replacement for the faulty cap. Thanks for your help seco services.