A little advice, pretty please, to the collective brain that is LCB!

I have a Worcester 24CDi - about 8 or so yrs old.

It has, over the last couple of years leaked pressure - seems to be ok when it is running, the pressure stays between 2 and 3 bar.
when it has been off for an hour or so, the pressure has slipped down to 0.5. Lately ( the last week or two) it drops right to nil.

The problem is, I am pretty sure, the overpressure valve, as there is nearly always a drip coming from the tail outside the house.
I have replaced this twice, once about 18 months ago, it was ok for a week after that, then it started loosing slightly again.
A couple of months ago I replaced it a second time, once again, it was ok for a few days, then it started leaking again.

Is there a possibility the valves I am putting on are poor quality? (They were both supplied from ebay plumbing suppliers - different
ones each time, but the valves were new and right for this boiler).


The only other thing I have tried is capping the tail - yeah, I know - a bit dodgy, but its just something I tried for a few hours - the pressure
just kept climbing to full scale (4.0) then I turned it off! The pressure held ok with the boiler off, though.

Any comments will be gratefully received......

Check the expansion vessel. It may have lost pressure or ruptured inside.
Check the filling loop is not letting by.
Replace 3 bar it will be knackered now.
Pressure should be 1 bar cold. Rising to approx 2 bar hot.
Al

It sound to me like the pressure vessel has gone as Wadders suggested. Mine went on the same boiler and if you are lucky enough to have room on the LHS of the boiler, then you can replace it without having to take half the boiler apart!
With regards to the safety valve, once they have 'operated' you tend to get bits of cr*p that's in the system in the valve which causes it not to seat and hence it allows water out of the system. (Of course yours could be operating due to over pressure!)

Have a good look at the big red expansion vessel for any signs of corrosion or leaks as a starting point. I assume you are 'looking' , but remember what Gas Safe is all about though.

Cheers, Nick

Check the shraeder valve on the expansion vessel for air pressure. If any water comes out of this valve you will need to replace the pressure vessel. They aren't very expensive or difficult to change

Had a similar issue last week
Schroeder valve, pence to replace
The dripping from theories sure relief valve however was more of a flood when mine went.

Thanks for the info, guys - I will have a serious look at it now (probably early next week now due to work commitments). - I was convinced it had to be the relief valve - but I'm not really surprised so many of you think it may be the expansion chamber - would that account for the pressure dropping I've described?

There is a wall cupoard to the left of the boiler, but removing that to help access wouldn't be a problem.

Once again, thanks to all of you.

This sounds similar to my issue a week a so ago. In my case the bladder pressure was too high which meant the expansion wasnt being used. The pressure would then go over pressure when hot an vent a little it then went off overnight cooled down and pressure dropped below 0.5 and then the boiler wouldnt resart. I had to then top it up a small amount and then it would work for a while until the ext cold day. Once i reduced the pressure on he expansion it was all ok.

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Originally posted by watsonpj
This sounds similar to my issue a week a so ago. In my case the bladder pressure was too high

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