Cold radiator after drain

11 Sep 2007
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United Kingdom
Hi Guys,

Drained central heating to fix a leak on one of the pipes, refilled as normal, bleeding all rads, BUT!

One radiator will just not get hot! I have bled the radiator, there is water in it, flow and return are cold. The rad in question has a drain valve on it, so to test I drained some water out, got hot water to the valve, thought this has cleared an airlock, but after about 10 mins the pipe went cold again, so obviously water is not flowing through the rad. No air is coming out when I try to bleed it.

Any suggestions?

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try turning off all the rads that are working and see if you clear any air to this rad
Sorry, forgot to put in original post, already tried that and nothing happened!
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I had this recently on a job,tried the shut them all down method but still stone cold
It had the draincock, I had used to drain the system,on one side

I opened the draincock and got loads of air through and all was fine

Sounds like you need to draw the air out
You could try opening the bleed screw with a cup or something and take a litre or so out
Or opening one of the suspect rad valves into a bucket,obviously with rad removed (unless there is room to move the valve out)
and wait for the air...could be either side

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