Two of the eight radiators in my house get only lukewarm. All eight radiators have been bled. The inlet pipes to the two dodgy radiators are red hot so the problem appears to be with the valves. I have tried to loosen one of the valves by removing the plastic cover and then tapping the top of the valve gently with a hammer but there was no improvement.
I have read plenty of advice on the web about loosening the pin in the valve but this seems to be inaccessible.
Could anybody advise what I can do to get the radiators working?