Worcester 24i Junior Pressure rising

3 Dec 2010
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United Kingdom
I have had an ongoing problem with my boiler that has seen visits from two different plumbers and now the second plumber has referred me to a third.

About a month or so ago I noticed that the pressure was rising when the heating was switched off. After visiting this forum I came to the conclusion that it was either the filling loop leaking or a hole in the heat exchange unit. I disconnected the mains water supply to the boiler and pressure stopped rising which didn't really help me identify the problem. I had my boiler serviced about 6 months ago and while he was servicing it he replaced the old steel filling loop with the key recharge system. I got the same plumber back and he re-pressurised the PRV and checked the filling recharge thing and said it was impossible for water to get into the system when the key was removed so it must be the heat exchange unit. My mother in law knows a plumber so she asked him to come over and have a look. He called me and said he had had a look at the recharge key thing and emptied and some water out and refilled it. Following that the pressure remained constant for over 24 hours so I assumed that the problem had been with the filling loop thing. The next day I noticed that the pressure began to rise again and it seems to be rising faster as the days go on. I called the plumber back and asked if he could replace the key charge loop thing with an new one in case it was faulty and he said he was uncomfortable doing this in case it did not work. Now I am at a loss. To add to the problems the PRV is stuck open now so I don't really have much of an idea of how much water is getting into the system. My question is :- What do I do now? Can the filling loop key thing let water into the system even when the key is removed? Am I doing damage to my system by continuously adding new water to the system? I really want to get this fixed and it is getting colder and colder and closer to Christmas. Also, if the problem was a hole in the heat exchange unit could the plumber have stopped the pressure from rising in any way when he came to look at it. Any help would be appreciated.

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it certainly sounds like the heat exch as no water can enter the system with the key removed....water would gush out...the key is the bridge if you will.

Worcester do a call out for £210 includes all parts. dont know the price of a heat ex but would think its up there! for this to happen you may have a sludged up system. if i was doing the job i would take a water sample and at least then if advised properly you could remedy it and it wouldnt happen to the new one.

The engineer cant do much about it. the only way to stop it is turn off the cold bulkhead but then you would have no h/w. hope this helps
Thanks for advice it's much appreciated. How do I turn off the cold bulkhead please? Been switching off whole house water supply from tap outside. It's getting tedious now.
the cold feed going into the boiler has an isolation valve, if you get a flat head screwdriver turn it a quarter turn. i wouldnt bother if i was you because then you'll get not hot water. the damage is done now..you need a new heat/ex. no more damage can be done just use the boiler as normal till you get it fixed!
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Thanks again for your help. The main problem I have is that the pressure seems to be increasing faster now than it was and I am concerned about the pressure getting to high. Even with the pressure relief valve open the pressure still rises to above I have spoken to Worcester and they say they should be able to get an engineer out on Tursday for £210 including parts like you said. Is it ok to turn the isolation valve off and on for the next few days. Luckily I have a downstairs bathroom with the kitchen next door (boiler is in bathroom) so it wouldnt be too much trouble to isolate supply until hot water needed. I will be glad when this is fixed.
Thanks again

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