Radiator cold until bled

11 Nov 2010
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United Kingdom
Hopefully someone can help!

One radiator is always cold. The pipe to the lockshield valve is slightly warm, pipe to the thermostatic valve is cold - both are fully open.

Thermostatic valve pin moves freely and have tapped it a few times to make sure.

If I bleed the radiator and leave the water flowing it starts to get a bit warm at the top and both pipes get hot

Many thanks
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if the rads full of air before you bleed it then it won't circulate till bled.
Thanks - water starts flowing as soon as I turn the bleed key!

Just tried closing the shieldlock valve and leaving the thermostat valve open - water flows from the bleed valve but if I push the therm valve pin in it stops - so I assume the valve is actually working! The water coming out of the bleed valve is warn too.

Am I right in assuming that the radiator may be sludged up?
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