Question for any plumbers out there

need_my_wedge

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Moved into a “new” house last week. The ensuite has a vertical towel radiator that has an airlock. I’ve bled it twice a day for a week and still can’t clear it. The top two bars won’t heat and no matter how long I leave the bleed valve open… no water escapes.

Anyone know how i can get rid of this flippin airlock?

Thanks in advance.
 

Whereditgo

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Pressure is fine, system boiler and no issues with hot water to either shower or taps.

Not the same thing. The domestic hot water will be supplied from mains cold water, the system boiler heating circuit is almost certainly a pressurised system (as opposed to open vented).

The top of the towel radiator is quite likely the highest point in the system, so it could be a pressure issue (though most system boilers would have a pressure 'lock-out' safety device).
 

need_my_wedge

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Not the same thing. The domestic hot water will be supplied from mains cold water, the system boiler heating circuit is almost certainly a pressurised system (as opposed to open vented).

The top of the towel radiator is quite likely the highest point in the system, so it could be a pressure issue (though most system boilers would have a pressure 'lock-out' safety device).
Pretty much is top of the house. highest point across all radiators. No idea about pressure lock-out.

I've bled it every day for a week now, this morning was the first time that the top bar fully heated, but still not sending any water out of the bleed as I would normally expect.
 

Whereditgo

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If the system is a pressurised (unvented) system then there will almost certainly be a pressure gauge on the boiler, as you bleed the system you will have to manually add water (there is usually a 'cold fill' link pipe with two 1/4 turn valves and a flexible pipe connecting between the cold water and heating pipework) to replace the air that you are letting out. System pressure should be circa 1.2 bar when the system is cold.

If the heating circuit is a vented system, there will be a small cold water tank (feed and expansion tank), usually in a loft space, that will top up any water lost. The tank will be fed via a float valve of some description to top up with cold water and there will be an expansion pipe that is installed so that water can discharge back over the top of the tank as the heating system water heats up and expands. Because the float valve actually operates very rarely it is common for them so stick/seize and the tank to eventually go dry. Then there is insufficient water to replace any air that is bled out.

It could simply be that as the top of the towel rail is relatively close in height to the feed and expansion tank the pressure differential is very small (2m of height is just less than 0.2 bar) and will be very slow to bleed, in which case doing as BiMGuy suggests will help speed up the bleed process.
 

HomecountiesJohn

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I had a similar problem with my relatively new system. I had British Gas round who told me I needed a Powerflush, £650 later and we still had the same problem. We did notice that some radiators were a lot hotter after the Powerflush, just not the ensuite radiator in the attic.

After talking to a guy in the bar one Saturday afternoon, he recommended me a great guy who came out and fixed it by balancing the system, laymans terms, he turned the downstairs radiators down which helped push the the hot water upto the attic.

Another £140 but I was extremely pleased that he’d rectified the problem.
 
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