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  • Any boiler experts pls?
  • Drapoon
    Free Member

    Save me from the clutches of Npower pls chaps. Got an engineer coming round to look at my boiler today & don’t want my pants pulling down! 😉
    Basically we have been in this house since September. Boiler is a Worcestor combi Boiler.
    Central heating has always worked A1
    Hot water was fine in the beginning but since early December we have had problems…
    The shower (non- electric) started to be very sporadic, hot water would go cold then hot & so forth.
    The problem then escalated to 1st 30 seconds pumping out boiling water followed by Baltic water – if you leave the shower running for 5 mins then turn it off for 20 mins & come back to it, hot water is available ( but again sporadic). The same issues can be said for the bathroom sink hot tap.
    Now the hot tap in the kitchen is doing the same .
    I’ve noticed that there is no “clunk” of valves diverting(?) coming from the boiler anymore when you switch the hot taps on
    As you can imaging planning your life around the shower working is getting a pain – the only benefits being a nice wake up stone cold shower to get you in the mood to go to work!
    Shifting mud from a winter ride is also difficult when using cold water – lol
    I praying it’s a cheap fix – our 1st house & we bought at one of the worst times!
    Any ideas?

    Free Member

    I am not an expert, but I do know that Npower quoted double what anyone else did for installing a new boiler in my place last year. 😐

    Free Member

    Had the same thing happen ove the Christmas period…..sounds like the diverter valve.

    I ended up joining a yearly maintenance scheme for £200 as a mate who is a plumber says that my boiler is a pig to work on and as I have only just moved in to the place it might make financial sense to get everything sorted under a warranty.

    Good luck.

    Free Member

    Oh and the plumber who came round was only here for 40 mins….so should be easily rectifiable.

    Free Member

    Sounds like the divert valve.

    It works by having the ‘hot’ circuit and the ‘cold’ circuit on opposite sides of a rubber diaphragm. When you open a hot tap (or the shower) the ‘hot’ pressure drops, and the diaphragm moves. It is attached to a shaft, which pokes out of the end of the valve body, and in turn pushes a microswitch which will fire up the boiler thus turning the ‘hot’ water hot.

    The diaphragm eventually breaks down, and stops moving. It can shift on the initial demand, then the pressure equalises and it moves back – and the boiler thinks you don’t need any more hot water, and shuts off.

    I have had to replace 2 of these on my 4-year old Worcester Bosch 28CDi.

    It is a DIY-able job, and doesn’t involve touching the Gas side. However, I wouldn’t recommend it if you are not in possession of reasonable DIY skills.

    The valve is pretty buried in the 28CDI – the rest look similar. Lots of things to take out before you get to the valve. Lots of potential leaks when reassembling.

    Replacement valves are about £180 IIRC, but last time I did one, I got a replacement diaphragm for £15. 1st time took me about 3 hours.

    There is a decent repair manual available online here –

    You can do a ‘quick fix’ if you glue a lump of something onto the end of the actuator shaft, but it will only buy you about a week at best.


    Free Member

    Cheers guys.

    I am hoping the npower guy will diagnose (as it’s a free service)then I will get some quotes for th ework to be carried out

    Thanks for all the advice – if it is the diverter valve I may hav a crack at it myself…!

    many thanks

    Free Member

    Drapoon – if it’s a 28CDi (or similar – look at the service manual link) then feel free to email me if you are having a bash and get stuck.

    Free Member

    I had some problems with my 10 year old boiler last year, I contacted Worcester Bosch and took out one of their service plans with the initial call out. They repaired it at a very reasonable cost.

    Another major part went wrong later in the year so they came out under the service plan and changed everything apart from the outer case and the gas valve.
    Great value. Good Luck.

    Free Member

    Right I’m back after having the npower guy out….

    It is the diverter valve that’s the problem. However it turns out I’m covered under their call out package that I got free for one year! He’s fitting it tomorrow – I called npower myself to check everthing was fine & it is. If 2mrw goes well it’ll be the 1st time summits gone in my favour with a utility company.

    He did mention we might want to start saving for a new boiler, it’s 14 years old & starting to show it. A worcester 230

    Many thanks all – espcially dave 😉

    Full Member

    sm: how much did Worcester Bosch charge for the service plan, if you don’t mind me asking?

    We’ve also got an ageing Worcester 24i combi and a service plan seems like a sensible precaution.

    Full Member

    If you need a new one, get a microCHP unit. It will provide your hot water and generate your electricity on the side ‘for free’.

    Full Member

    Jimmy- tell me more- I’m in the market for a new boiler very soon.

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