cold radiator

[fruitsalad]

just put the heating on and one of the bedroom rads is cold the rest are ok tried bleeding it, still not getting warm any idea what the problem could be?

[The Builder]

Could need balancing Fruity ....................... first, try turning all the other rads down and then see if it warms up

[AlBags]

Yes .. Turn the lockshield valves (opp end to control valve) down starting at the NEAREST to the Pump, toabout 1/2 turn open. Work backwards in system distance to the radiator in question.
Bleed again if necessary.
Is pipework microbore (8mm or 10mm?) or 15mm copper?

[AlBags]

As you go to each rad further from the pump, open the lockshield a bit more, so you have at least 2 turns open at furthest rad.

[jubieanna]

could just need bleeding to get air lock out

[AlBags]

That's right .. It could .. But balancing system like I was explaining will help all rads heat up evenly, and flow to extreme rads will be same as through nearest.

[jubieanna]

sorry just realised you've tried bleeding it. listen to albags he seems to know what he's talking about. once ive bled it im stumped!

[AlBags]

Yep .. Thanks.
Been doing it for years. That will help flow and make easier to get hot water through it.
If it's a Sealed Pressurised system (Combi OR conventional boiler) make sure system pressure is kept topped up to around 0.8-1.0Bar on the gauge using the fill loop that should be there attached to mains cold.

[fruitsalad]

The Builder, tried it but still no getting warm, thanks anyway

[alavahalf]

If you have'nt been using your heating for some months. Was the rad in question turned off at the thermostatic radiator valve... If it was.. they often get stuck in the closed position.
I would try supporting the back of the valve with the head of a hammer, and just hit the body of the valve with something ... the valves often stick closed after long periods of not being used.

[AlBags]

Correct .. forgot that one.... A TRV valve can stick shut ...
Although if you unclamp the head control, you can usually wriggle the little pin that sticks up. It should be sprung upwards constantly.

[sddsddean]

I'd go for the TRV. At least one of ours gets stuck every year. If you unscrew the knurled collar below the control bit( that usually looks like an upside down plastic cup) and take the whole plastic bit off, you will see the little brass pin . Tap it VERY gently with something (like a pin hammer) and it should pop up. Screw the control back on...job done.