one upstairs radiator cools down. Why?

frogbottler

No problems with any of the other radiators upstairs or downstairs. But one bedroom radiator is hot only for the first couple of hours then starts to cool down until it is only lukewarm and remains lukewarm. At this stage there are no hotspots on the radiator at all - it is lukewarm all over.

Both the pipes at the bottom of the radiator remain hot throughout.

My knowledge only extends to bleeding the radiator which I've done but it hasn't improved

grateful for any advice.

Cheers and happy Christmas

Browntoa

I've had a thermostatic valve that malfuntioned causing the same

only way to change them is to drain down the whole system

frogbottler

Thanks, Browntoa. Think I'll postpone it until spring before draining it. My "to do" list just keeps on growing