I have 13 year old Worcester 24/28cdi rsf combination boiler. The pressure gauge keeps dropping from the 1.5 bar setting and I have to top up every other day. Could this be a faulty expansion vessel? I tried to test the pressure in the vessel, but the schrader valve is too near a small copper pipe that is directly underneath. I have no visible leaks coming from the ceiling and the pipework downstairs is above the floorboards and no leaks can be seen from any of the pipes or radiators there either. I have a one pipe system apparently. I have checked for water coming from the pressure relief valve outlet and it is dry. Any help would be much appreciated! If the vessel is deemed to be faulty I am confident I can renew it with a new one, but want to make sure it is faulty first. Thanks!
Is my expansion vessel faulty?
- Thread starter didgeradoo4719
- Start date
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It might just need re-charging
put a ballon on end pipe and if it fills with water yes if not no
Hi. I assume the balloon goes over the overflow pipe that goes out of my outside wall onto the driveway? Sounds like a great idea! I'll let you know if I get any water over the next couple of days. Thanks.
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Hi. I have been told to try and do exactly what you say, but the problem is getting a gauge on the schrader valve to check the pressure. I tried levering up the vessel to create more room, but it didn't help. Whoever assembled the boiler didn't place the expansion vessel in a way to make the valve accessible. I don't know how a service engineer would manage to check it either! Oh well, I'm going to try the balloon method and see if I get any water in it. Thanks for you input!
after repressurising the system to 1 bar and the all the rads bled, turn on the heating and watch the boiler pressure guage if it rises up to 3bar then yes the EV is faulty.
if the pressure doesnt rise sharply then its unlikly to be the EV at fault
Matt
if the pressure doesnt rise sharply then its unlikly to be the EV at fault
Matt
Thanks for that information. I'll do it tomorrow and let you know the pressure reading I get. I see to remember seeing aroung 2 bar the last time the heating was on. Is this figure normal? If so then is the EV ok? Thanks again.
Some versions of the CDi have the schrader valve too close to pipework as you have found. You have to disconnect the vessel pipe connection, cut the tywrap and lever the vessel across. Whilst you are pumping up the vessel water will flow from the vessel...so you need to fabricate some pipework to collect it. Great boilers aren't they 
Hi. I checked the pressure gauge on the boiler this morning and it had stayed on the 1 bar mark! I switched the heating on, waited an hour and then checked the pressure gauge again. It had increased to just under the 2.5 bar mark. Is this acceptable? I've now switched the central heating off and I'll check the pressure gauge again once the system is full cold and let you know what it is. Thanks for all your help!
Hi. Thanks for that advice. I'm going to see what the pressure gauge reading is once the system has cooled down later today. Please read my reply to Matt1e below! Thanks for you input.
Hi. Thanks for that advice. I'm going to see what the pressure gauge reading is once the system has cooled down later today. Please read my reply to Matt1e below! Thanks for you input.
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Read more: //www.diynot.com/forums/viewtopic.php?p=1962721#1962721#ixzz1JsuQZTe9
Some versions of the CDi have the schrader valve too close to pipework as you have found. You have to disconnect the vessel pipe connection, cut the tywrap and lever the vessel across. Whilst you are pumping up the vessel water will flow from the vessel...so you need to fabricate some pipework to collect it. Great boilers aren't they
Hi. Boiler now maintaining pressure at 1 bar, which is what it was set at when first installed. I think (although I'm probably wrong!) that 1.5 bar is just too high for my boiler unless the expansion vessel has a weakened diaphram? I'll continue to monitor it for a few weeks and if it stays at 1 bar then I guess all is well! Thanks to all who replied and helped with my problem!
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