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combi boiler keeps losing pressure


 
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fitzy

from United Kingdom

Joined: 10 Oct 2005
Posts: 2
Location: Blackpool,
United Kingdom

PostPosted: Mon Oct 10, 2005 9:54 pm Reply with quote

my combi boiler (worcester 9.24 electronic) keeps losing pressure i have checked all related pipework and radiators for leaks but found none.
while the system is running the outside overflow pipe has a steady drip/flow coming throught it.
when the the system is started say for hot water it makes a hell of a racket and i have to repressurize it and push the reset button before it will run can any one help thanks. icon_sad.gif
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DarkInferno

from United Kingdom

Joined: 08 Mar 2005
Posts: 121
Location: West Midlands,
United Kingdom

PostPosted: Mon Oct 10, 2005 10:32 pm Reply with quote

fitzy wrote:
... for leaks but found none.

Found it!
fitzy wrote:
... while the system is running the outside overflow pipe has a steady drip/flow coming throught it.

Probable case is faulty/depressurised expansion vessel, which sounds like it has gunked up the PRV seal too.
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meldrew's_mate

from British Virgin Islands

Joined: 04 Oct 2005
Posts: 555
Location: British Virgin Islands

PostPosted: Tue Oct 11, 2005 8:24 am Reply with quote

Fitzy, take the white front cover off and find the red expansion vessel, about 12" x 6". Locate the inflation point and stick a matchstick in it like you were letting down a neighbour's tyres (if you're stuck ask a teenage hoody for help). If water comes out you need a new vessel. If nothing, or just air comes out it may be salvageable.....

....Take a bike tyre pump and put about 20 good strokes into it, watching the pressure gauge. If it goes up put another 30 in, or stop when the pressure gets to 2 bar. Bleed the upstairs rads and recheck the pressure, pump more air in to bring pressure back to 1 bar.....

....Check the PRV outlet, if it still drips you need a new PRV. If not turn the heating on and watch the gauge as it warms up. If it goes over 2.5 bar wait for it to cool, then put 20 more strokes of air in, re-bleed to get pressure down to 1 bar, and re-try.

If some is good, more is not necessarily better, so don't overdo this.

Put the cover back on.
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fitzy

from United Kingdom

Joined: 10 Oct 2005
Posts: 2
Location: Blackpool,
United Kingdom

PostPosted: Wed Oct 12, 2005 9:34 am Reply with quote

i have tried the expansion vessel and water is spraying out as you suggest i may need to replace it is this expensive and is it possible i can purchase one and do the job myself or do i call in an expert icon_question.gif
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Agile

from United Kingdom

Joined: 26 Jun 2004
Posts: 52973
Location: London,
United Kingdom
Thanked: 3343 times

PostPosted: Wed Oct 12, 2005 5:13 pm Reply with quote

Its a very old boilerand you should be planning to replace it!

A cheaper solution is to fit a stand alone ex vessel on the heating circuit.

Or as a temporary solution ( 12 months ? ) isolate a rad and take 8 litres of water then put it back WITHOUT bleeding, the air at the top will then act as the ex vessel.


Tony
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thumper1

from United Kingdom

Joined: 11 Feb 2009
Posts: 1
Location: Leicester,
United Kingdom

PostPosted: Wed Feb 11, 2009 10:00 am Reply with quote

meldrew's_mate wrote:
Fitzy, take the white front cover off and find the red expansion vessel, about 12" x 6". Locate the inflation point and stick a matchstick in it like you were letting down a neighbour's tyres (if you're stuck ask a teenage hoody for help). If water comes out you need a new vessel. If nothing, or just air comes out it may be salvageable.....

....Take a bike tyre pump and put about 20 good strokes into it, watching the pressure gauge. If it goes up put another 30 in, or stop when the pressure gets to 2 bar. Bleed the upstairs rads and recheck the pressure, pump more air in to bring pressure back to 1 bar.....

....Check the PRV outlet, if it still drips you need a new PRV. If not turn the heating on and watch the gauge as it warms up. If it goes over 2.5 bar wait for it to cool, then put 20 more strokes of air in, re-bleed to get pressure down to 1 bar, and re-try.

If some is good, more is not necessarily better, so don't overdo this.

Put the cover back on.
I have the same peoblem. May seem like a silly question, can I replace the valve assuming its the the same/similar to bike tyre valve<a silly question
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