Expansion pipe discharge when heating turns off

jfk · 27 Jul 2007

Hi I have a problem with the header tank to the central heating overflowing. I have drained and run the system through and refilled. I have now noticed that at the point of the heating turning off it discharges water into the the heating header tank.
I have also noticed that the radiator closest to the airing cupboard only warms through one pipe, this is also the same with the hot water cylinder. The top pipe entering the coil is hot, the bottom is cold (luke warm at best).
Any advice on how to test and rectify the problem, I have considerd that their may be a blockage in the feed pipe but would like advise before changing pipes.

Dan Robinson · 27 Jul 2007

Sounds like a sludge problem as well as a possible pipe layout problem. Any pictures available?

jfk · 28 Jul 2007

Sorry no pics, the feed is 15mm dropping down in to the heating system and t`ing of to the lower pipe entering the coil, expansion runs on 15mm t`ing of to the pipe entering the top part of the coil. Would you think the blockage was somewhere along the 1st section of feed before exiting under the floor in airing cupboard.
My 1st theory was to replace the pipework running from header tank down and upto the rad next to airing cupboard that heats only through the one pipe?

Dan Robinson · 28 Jul 2007

expansion runs on 15mm t`ing of to the pipe entering the top part of the coil

That's not good for a start.

Should be 22mm.

gas4you · 28 Jul 2007

Is this an old gravity primary system or fully pumped? If fully pumped I would replace pipe work to header tank and install an air seperator such as a Myson Aerjec.

jfk · 28 Jul 2007

Hi I fought it should have been 22mm.
It is an old system. Their is no 3 port valve in the airing cupboard infact im not sure where it is and their is a pump which is down stairs above the boiler.
It apparantly used to work fine untill she had someone in to power flush the system (sounds like a bodge flush tho they had to replace the pump the next day probably didnt bleed it).

gas4you · 28 Jul 2007

Do you have 4 pipes coming off the boiler or 2?

jfk · 29 Jul 2007

2 pipes flow and return its an old glow worm boiler but not sure wich model.

gas4you · 29 Jul 2007

Sounds like a very basic pumped system then.

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Expansion pipe discharge when heating turns off

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