Quick advice please - central heating


Plumber has just refitted one rad which has been off for decorating. Now getting lots of air in upstairs rads and overflow from the CH header tank to the outside of house. Lots of bubbling sounds from rads. It's an old gravity fed system.
Advice appreciated. Jerry
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If the only work has been the removal and refitting of one rad and this has no leaks then it is probably an air lock.
Try bleeding the rads in turn with all others turned off. Having the pump running while you do this may help force air out of the pipes. Start downstairs.
I would also check that the header tank has water in it before starting. Maybe the plumber has replaced the rad and bled it but the header tank did not fill up and so he has introduced air into the system by filling the replaced rad with water from upstairs rads.
HTH
Adam
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Jerry and Ce wrote:

I found the Re-filling section on this page helpful. http://www.diyfixit.co.uk/nflash/centralheating/CHDraining/draining.htm
When I completely removed a rad (capped off pipes) I had to drain the system and then re-fill it. I refilled(or so I thought) the rads, then I had overflow from the header tank too. I have no isolation valve by the header tank, I had to shut the water off at the mains.
The ballcock, was so used to being level(ish) it had jammed when the tank was emptied, and when I refilled the tank, the water just went up and over it, A little wiggling about sorted it out. When I was bleeding the rads, I left the water turned off, as I knew there was a whole overfilled tank of water. Then spent about an hour refilling the reads. I had to go round them 3 times in turn before they were full, popping into the loft to check the water level & I turned the water on again at the end of the first filling session.
I bled the rads again each day for 2 days and it seems fine now. One rad that wasn't working before is now nice and hot. :-) BONUS!
When you are re-filling you can feel the air coming out, and hear the header tank filling up again, until the water comes out of the bleed valve. You think it's full, but when you go back round again, more air has arrived. Good fun if you like black water :-)
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Thanks for your help guys, we have identified the problem. The plumber fitted an Aladdin auto air bleed valve to the rad when he replaced it because we were having to bleed this rad every week at least. Unfortunately the Aladdin seems to be crap and was actually feeding the rad with air. Removed it and problem gone. Doesn't it drive you mental?!
Jerry
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If you still have to bleed this rad weekly (time will tell) then you have a problem.
Adam
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Of what nature? Obviously I realise that it shouldn't be necessary, but the effort required to fix would, I imagine, be out of proportion to the problem?
Jerry
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A leak. The bigger problem is that when you bleed the rad you are introducing fresh water into the system. This will dilute any inhibitor in the system and cause corrosion.
Adam
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Thanks Adam. I appreciate your advice. Will see how we go. Jerry
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