cold downstairs radiator

5 Nov 2007
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United Kingdom
Has anyone got any thoughts on why my living room radiator is only ever warm and not hot.

I have a potterton boiler with a tank upstairs the pump and the honeywell threeway valve also upstairs. The three radiators that are downstairs have two pipes each coming from upstairs 2 of the radiators get red hot, but the one in the living room only gets lukewarm. I have bled it several times but there is no air. So next i removed it flushed it out with a hosepipe until clean water came out. I then refitted it then bled it. hey presto it got hot for a day then went back to lukewarm.
Anyone any ideas
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If you turn off the upstairs rads, does it heat up? You could balance the syst. you say some rads are hot and one warm, so close down the lockshields a bit on the hot ones.

It might be clogged again
give it a chemical clean too
and my favourite, fit a Magnaclean to trap the rest of the black sediment
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Sorry another question the valves on all my radiators have got plastic pull of covers when i pull the covers off the valves are identical both sides. Which side is the lockshield or doesnt it matter.
Personally I prefer to turn on or off at the flow side and leave the return as the lockshield. Many will argue the necessity and say that it does not matter. Probably less important on an old open vent system.

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