Combi boiler problem

Discussion in 'Plumbers' Talk' started by unphased, Feb 4, 2017.

  1. KIAB

    KIAB Well-Known Member

    I reckon you would have same problems,but I don't do gas so could be wrong.
  2. unphased

    unphased Screwfix Select

    Its just odd that the boiler has ignored the room stat and jsut started pumping hot water round the CH permanently now. If the valve is stuck then it would also affect the HW as it would be struggling against itself? Does that make sense?
  3. terrymac

    terrymac Well-Known Member

    I wouldn't buy a pump if i were you.the pumps job is to circulate water and it would appear from what you have told us that your central heating is permanently on ,and assume all your radiators are fine. What makes you think the pump is causing your boiler to fire permanently ? That's a control issue
    KIAB likes this.
  4. I'm with the others, UP - I just don't see how it could be the pump.

    Cycling hot/cold on your DHW is a classic blocked P2P exchanger issue (something I've had plenty experience of...).

    However, the permanently running CH is weird - I can't see the diverter valve doing this as it isn't 'switched' afaIk. Ie, the valve is told by the boiler to divert to CH after the boiler has been told to come on by the room stat controls. (It's not like an external diverter valve on a 'conventional' boiler in which the room stat tells the valve to open and then the valve tells the boiler to come on.)

    I fear you need a good GasSafe - one fully familiar with GlowWorm ideally - I bet they'll diagnose the issue right away.
  5. nigel willson

    nigel willson Well-Known Member

    Why would you want to adjust it. It’s there to protect the boiler
  6. unphased

    unphased Screwfix Select

    Just an update. I am getting a 3-way valve kit and a diverter valve motor after a wasted journey to buy the pump. That was plain stupid on my part, it wasn't what I thought I was buying, I thought I was buying a pump and diverter valve combined. Just got completely confused with part numbers and stuff.

    Having now removed the heat exchanger to get access to the diverter motor there is no blockage whatsoever in the heat exchanger, it has to be the diverter valve. Anyway, I'll let you know.

    Im now getting these: and this
    Deleted member 33931 likes this.
  7. leesparkykent

    leesparkykent Well-Known Member

    That doesn't surprise me in the slightest ;)
    KIAB likes this.
  8. Blimey, UP - you're willing to get stuck in :)

    Fingers crossed, man :D
  9. The Teach

    The Teach Well-Known Member

    it does sound like the diverter valve is not sealing and the hot water pre heat is sending preheated hot water around the radiator circuit instead of the plate heat exchanger.

    The hot water preheat can be disabled by using - (minus button) on the fascia.
  10. retiredsparks

    retiredsparks Well-Known Member

    Interesting manifestation of symptoms and look forward to the actual fault being diagnosed and the least possible cost obviously... and the least disruption to his household.
    What concerns me is the fact that Un...said . "That was plain stupid on my part".
    Now, correct me if I am wrong...but if UN is going to start calling ..himself "stupid"....what are the rest of us going to do for the rest of the year ?
  11. retiredsparks

    retiredsparks Well-Known Member

    Un....I hope you have a
    magnaclean pro on that system....otherwise Mr K will be on you quicker than a rat up a drainpipe....
  12. unphased

    unphased Screwfix Select

    Just some feedback for closure. It was the diverter valve. The old RH valve had jammed solid in the one position. LH valve seemed okay but very black. As a precaution I also replaced the diverter valve motor. Parts as listed in #26.

    All working now. Hot water has never been so hot. Can have a nice shower now. :D

    Deleted member 33931 likes this.
  13. Dude!

    Two valves? What sort of combi is this?!
  14. unphased

    unphased Screwfix Select

    It's a monoblock, the valve is in two halves, LH and RH if you will. Don't ask me to explain it I'm a spark not a gas engineer.
    Deleted member 33931 likes this.
  15. unphased

    unphased Screwfix Select

    It's also cured the permanently firing heating and the on/off cycling overnight. Just comes on for a minute or so as it should to ward off cold climate in loft.
  16. Och I bet you're chuffed :)
  17. retiredsparks

    retiredsparks Well-Known Member

    Well done........always nice to be able to fettle these things ...
    what was the diverter valve type (pic)...and any special tools.....

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