r/DIYUK • u/CaptainPunderdog • 4h ago

Advice Boiler not repressurising after rad replacement

/r/askaplumber/comments/1wahlg9/boiler_not_repressurising_after_rad_replacement/
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u/Civil-Ad-1916 4h ago

It sounds like there’s a valve that’s not opening correctly. Have you been able to re-pressurise the system in the past?

Can you post a picture of your filling loop arrangement and any associated plumbing and valves on the boiler feed.

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u/CaptainPunderdog 4h ago

This is the underside - the two blue valves are the standard filling loop ones which I turned.

These valves are working correctly, because turning them without the loop in place causes water to come out.

The yellow one and left hand black on I am leaving well alone, but the right hand black one behind the blue one I opened and then opened both blue ones again but it didn't make any difference.

I can't remember repressurising it in the past, this is the first time I've taken a rad off in this house so I'm not sure whether I've done it before or not unfortunately.

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u/CaptainPunderdog 4h ago edited 4h ago

Well this is all very frustrating - I have tried again to fill it but this time with the heating on and it is now working, but with the heating off it still doesn't fill. Definitely feels like an issue with the boiler as opposed to something I've done.

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u/Complete_Desk_9173 4h ago

Sometimes the blue lever will spin on its shaft rather than turn it. You may have to remove lever and use pliers.
L/h lever should be horizontal to fill, r/h lever pointing toward you. Fill to 1 bar pressure.

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u/CaptainPunderdog 4h ago

I'm happy that both levers are turning, because if the filling loop isn't in place water comes out (at some pace) from both. I've turned them both to the open position in line with their relevant pipe to try and fill, which is the point that it gurgles but doesn't do anything. It seems to only actually refill when the heating is active.

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u/Plastic-Answer-5437 4h ago

i had a very similar issue, and it was just trial and error of filing and refilling starting with all the radiators open, vented them all, and then turned the heating on, but with the boiler dial starting on the lowest temp, and slowing brought it up to max (80 centigrade) over the course of 15-20mins. as my boiler was completely losing pressure if the central heating was turned off, even if the hot tap was running.

EDIT: by radiators open, i mean the TRVs on max (number five for most).