Cold radiator even with valves fully open

18 Apr 2016
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United Kingdom
I had a problem with a radiator that was only heating a small amount at the top. Today I took it off and flushed it out as best i could with a hose. I have now put the radiator back on, opened the bleed valve to let all the air out (to the point water starts to come out) then closed this, I have the manual control valve set to its highest, so fully open and the lockshield valve is also fully opened (as far anti-clockwise as it will go). There is however, no heat getting into the radiator. The pipe below the lockshield valve is very hot and as far as the union nut past the lockshield valve is also hot. I cannot figure out why it isn't heating up now? All other radiators in the whole house are fine. Does anyone have any suggestions where I might be going wrong?
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What type of valve is the " manual ' one ? Is it a TRV. ( big white plastic top with numbers ) ?? If so ,they have a pin that tends to get stuck .
With most of them ,you remove the plastic head ,you will see a small pin ,in the centre of the valve body. It should move down if you press on it ,and back up under spring pressure ( only moves a small amount). If it doesn't its closed !
P.s dont pull it up !!! But you can tap it lightly
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Ok so if I turn all rads in the house off except the cold one or is fine. As soon as I turn the others back on it starts to cool down. I guess it's a balancing issue then? The though is the largest in the house and has the valves fully open so I would have thought it would be hotter not cooler than the rest. Anyway I'll close the others a bit a see how it goes.
Close the lock shields on all rads ,except the one thats problematic. When it gets to FULL temperature ,go to one of the other rads and open its L/shield a tiny bit at a time until it reaches temp ( each time you open it a bit ,wait for minute to give time to see if it starts to heat before opening a bit more ). Then do all others ,one at a time, same process.

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