noisy baxi boiler help !

please can anybody help, i know that there are many threads on here for noisy boilers but non seem to be the same as mine.

my boiler is a baxi XXXXXX and is quite old, ok very old

when the system is running either hot water or heating its fine, the problem comes when it shuts off there is a lot of banging and whooshing and gluging sound coming from what i think is the overflow return pipe, if i touch the pipe i can feel the clunking through it, it sounds like there is boiling water trying to escape through it however there is nothing coming out of it, the banging last for about 10 minutes after the boiler has gone off.

iv checked the large and smal tanks in the loft and they are both full of water well over the outlet pipes, iv bled the pump and the rads to no effect, im wondering if some kind of cleanser would help, but not sure which to use or if it will make any diffrence, any help would be much appreciated, cheers simon

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sorry i meant to say its a baxi wm 55/3

Try Fernox Heavy Duty Restorer for a week, then do some flushing - see reference section.
Probably also another circulation problem - do a search on "sludge", "blocked feed pipe".
Presumably it's less of a racket if you turn the boiler stat down?

First thing I'd do, AFTER trying it with the boiler stat turned down, would be to put an aquavac on the vent pipe (over the feed cistern in the loft). Amazing what comes up!

Id suspect your boiler stat is faulty and is not shutting down till its far too hot. When you turn off your heating or hot water the pump stops and the latent heat in the heat exchanger is boiling the water.

The original question was posted 35 days ago!

One hopes they got it fixed some time ago!

Happy Christmas everyone!

Tony Glazier

The original question was posted 35 days ago!

Click to expand...

But what you won't know Tony, seeing as you've been so busy opening your record number of xmas presents, is that the OP has bumped the question back up several times, including yesterday, although the Mod seems to have removed these bumps now.

no i havent had it mended yet, iv just put up with the noise over xmas, ive found that there is hot water and steam coming from the overflow pipe, this happens when the boiler has just switched off for approx 5 mins, only a small amount of water but plenty of steam and burbling sounds. any one got any further ideas. cheers simon

Boiler stat does sound worn try running on min & see hoe hot the rads get. the last time i saw a similar thing the cold feed was blocked & when the pump shut off cold water from the vent came into the boiler & it didnt like it changed to steam. Does this happen evertime the boiler shuts down on its thermo stat or only when the clock or room stat turns it off.

sorted it was a blocked air seperator valve which eventually fractured and leaked all down my freshly plastered walls downstairs ! live and learn !