Worcester 24cdi boiler - high pressure problem

Discussion in 'Plumbers' Talk' started by jonny morris, Apr 15, 2010.

  1. jonny morris

    jonny morris New Member

    Hi,

    My boiler pressure keeps increasing to 3bar, which I guess is the house water pressure(?). I've been reducing it to 1.5bar but before you know it, it's back up at 3bar.

    Any ideas as to a quick fix?

    Many thanks in advance.

    Jon
     
  2. Bert Large

    Bert Large New Member

    Probably a pinhole in the DHW heat exchanger Johnny, allowing mains pressure water across into the heating circuit. It's a common problem on these boilers for some reason. The only fix is a new heat exchanger.
     
  3. jonny morris

    jonny morris New Member

    Thanks Bert.

    Which of the two heat exchangers are we talking about or could it be either? There's a big one on top for the radiators and a smaller one at the front that takes heat from the radiators to heat the water (I think).
     
  4. Notinmymums Forest

    Notinmymums Forest New Member

    bert is correct,mains pressure water passing over to c/h side......but first.....disconnect your means of filling the system(i.e filling link/filling link key)this could be letting by.....alternatively,isolate the mains inlet to your boiler by which ever means applies to you,check the guage,and check again in the morning.if guage is the same you have proved what bert has said....good luck to ya.
     
  5. Notinmymums Forest

    Notinmymums Forest New Member

    bert is talking about the small one(plate to plate)
     
  6. jonny morris

    jonny morris New Member

    Thanks Bob.

    The key is out. As the pressure only rises when the heating is on I presume you're suggesting I turn off the mains supply to the boiler, turn the heating on and see if the pressure does not rise to confirm the pin-hole theory?

    Thanks all for your help.

    Jon
     
  7. Bert Large

    Bert Large New Member

    Sorry, yes. I forgot to mention removing the filling loop. All the CDI's I've come across of these have that plastic key filling link & you twiddle your thumbs for half an hour while the old dear hunts high & low for the key ;)
     
  8. Notinmymums Forest

    Notinmymums Forest New Member

    ah ....right....thats the first time its been mentioned that the pressure only increases when the heating is on.....it sounds like the expansion vessel diaphragm is bust(check this by pressing the pin down in the car tyre type device on top of the vessel....if water comes out then its bust)maybe it just needs pumping up and has lost its charge....this vessel accomodates the (heated)expanded water when the heating is on!!!when you get it fixed i would also replace the pressure relief valve as it sounds like the boiler has been discharging frequently....best of luck.
     
  9. jonny morris

    jonny morris New Member

    Sorry, yes, the pressure only rises when the boiler is on. I pressed the car tyre type valve on the expansion vessel and no water came out. I guess my diaphragm is OK then?
     
  10. Bert Large

    Bert Large New Member

    Did you get any air out of the valve though Jonny ?
    The expansion vessel should contain a charge of air that becomes compressed when the heating water expands as it heats up.
     
  11. jonny morris

    jonny morris New Member

    Yes. Air came out but no water. The pressue on the dial went down, naturally.
     
  12. tackleburger

    tackleburger New Member

    Follow the MIs to recharge it. If it still does it check the charge may be the valve or a leak on the air side of the vessel.
     
  13. spongeblob

    spongeblob New Member

    Aye up Johnny!!used to love those animal programmes of yours,thank you. You need to get a Qualified Plumber out to sort out your little problem.?As I see it,the system needs to be shut down,to allow somebody with an ounce of brain to see whats going on with the xpansion vessel.End of. ;)
     
  14. jonny morris

    jonny morris New Member

    I was coming to that conclusion myself. I'd have a go if it had been straight-forward but it's not looking that way.

    Thanks all for your help.
     
  15. jonny morris

    jonny morris New Member

    Incidentally, how bad is it for the system to run at 3bar? Is this something I need sorted as soon as possible?
     
  16. doing a bit

    doing a bit New Member

    to check the exp vessel pressure first drop off the water side down to zero on the gauge, then with a tyre pressure gauge check the exp vessel pressure, should be 10PSI , if not pump it up to 10PSI , then refill the system with water up to 1 BAR on the gauge, should do the trick ;)
     
  17. doing a bit

    doing a bit New Member

    oh and you have probably lost most of your rust inhibitor via the relief valve so put some more in :)
     
  18. Notinmymums Forest

    Notinmymums Forest New Member

    could well be that the tube/pipe connecting the vessel to the system within the boiler is blocked.....therefore the vessel is not doing its job cause its effectively isolated.....just a thought.
     
  19. jonny morris

    jonny morris New Member

    I turned off the water pressure and checked the expansion vessel pressure. It's at 4PSI. Do I just pump it with my car tyre foot pump?
     
  20. doing a bit

    doing a bit New Member

    yes use a foot pump , inflate to 10PSI , then recharge the water side
     

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