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LPG combi boiler radiators won't bleed

Postby Pete2583 » Sat Oct 16, 2021 3:26 pm

Hello all.

So I've got a bit of an issue with my heating system. My plumber is also scratching his head so thought I'd ask in here. Maybe someone else has come across this.

This might be a long post as I want to get as much information in as possible.

Recently bought an 80's bungalow which had oil fired central heating. Ripped that out and replaced with LPG combi boiler. Heating seemed to work with all radiators working, although I never fully tested the system.

I then had some other work done. A few pipes were modified: hot and cold feed to kitchen sink. Hot and cold feed coming into the property had a t put on diverting some water to a new thermostatic mixer shower.

The system was drained and left empty for a few months, with all radiators taken off to allow plasterers to come in.

One radiator, in the bathroom was removed and pipes modified to install a towel rail.

Radiators all went back on, system was flushed and new anti-corrosion was put into the system.

Now, all the radiators work, but 3 of them only warm up at the bottom. When you release the bleed valve no air or water escapes.

I should probably point out I live in a bungalow. The boiler is in my garage and enters the property through the roof then goes down a wall, under my floor then onto all my radiators.

I think the first radiator on my system is in the kitchen, from there I believe it runs in a clockwork direction around the house. So kitchen, dining room, living room 1, living room 2, toilet room then bathroom where the new towel rail is fitted. All these radiators work. From there it goes to bedroom 1, bedroom 2 then bedroom 3. These radiators are the ones causing me an issue, hot water definitely flows through them as they do get hot at the bottom. If I crack the pipes on the radiator there is water there, although without risking ruining my brand new carpet I couldn't tell you how much pressure is in that water.

So any idea what could be causing the problem? At Central heating entry and return I have bleed valves which are opened so I would assume it wouldn't be caused by an air lock buy could be wrong? Any ideas how I might fix it? I fell out with my original plumber so haven't got him to come back and check but I could if I really had to. My new plumber has done some great work for me and head corrected some issue from the first plumber so I do have confidence in him but he is scratching his head a bit as to what the problem could be so any help would be gratefully received.

Pete.
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Postby ericmark » Sat Oct 16, 2021 9:19 pm

First thought is air lock, you may be lucky and turning radiators off may give it enough extra push, but the normal is to bleed each radiator twice, once with feed turned off, and once with return turned off.
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Postby Pete2583 » Wed Oct 20, 2021 1:08 pm

Ok cheers. I'll try that now. I'll let you know how that goes.

Wish me luck. Lol.

Cheers. Pete.
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Postby Pete2583 » Wed Oct 20, 2021 5:41 pm

Well that's had no effect on the 3 problem radiators. I rebled the whole system and I did get some more air out of some of the others. One of the non-problematic radiators seems to just leak air and water from the bleed valve which was a bit weird.

I guess it's time to call the plumber back. My boiler is due a service soon so I'll get them to do that while they are here.

Cheers. Pete.
Pete2583
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