Glow worm flexicom 18hx pump will not turn off

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Jj_472
Jj_472 Posts: 5 Forumite
in In my home (includes DIY) MoneySaving
Hi all,

When turning off the hot water and heating to our boiler I can see the valves turn off correctly. The boiler flame light goes off and we wait about 5minutes. The pump then stops... for about 5 seconds then starts up again and continues until I turn the boiler off at the mains. When the pump starts again there is no boiler lit light so it seems the pump is continuously running. Have left this on for a day and it still did not switch off

The pump within the boiler is a grundfos pump

Any ideas would be greatly appreciated.

I can send a video if this helps :)
Many thanks
James

Comments

  • Alex1983
    Alex1983 Posts: 958 Forumite
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    When it's doing it next press and hold the minus button for a few seconds and it will flash S and a number....let us know what number is showing. It will tell what the boiler is on for
  • Jj_472
    Jj_472 Posts: 5 Forumite
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    Hi Alex,

    When holding the button and leaving the boiler to run it's cycle I get error codes s07-pump overrun then it stops and turns off for 5 seconds giving the error s97- water pressure sensor check is running demand(shape heating is blocked).
    After that it starts the cycle again going in sequence from s2 error to s7 error.

    Not sure if this helps but we have had the pcb new low pressure sensor switch, new ignition sense probe and lead,new ignition transformer, new circulation pump unit with pressure release valve. THis was all done at the end of Feb. The issue only started after this.
  • Alex1983
    Alex1983 Posts: 958 Forumite
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    These aren't error codes there status codes it tells you what the boiler is doing. If it's going s2 s3 s4 then the boiler is firing up. It's getting a demand from somewhere, I would guess you have a issue in your airing cupboard. Have you got 2 zone valves in you airing cupboard or a 3 way valve.
  • Jj_472
    Jj_472 Posts: 5 Forumite
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    Hi Alex I have 2 Drayton zone valves.
    1 for the hot water 1 for the heating.
    They are controlled by a nest thermostat. I can see them moving from a to b with no problem and viceversa.
  • Alex1983
    Alex1983 Posts: 958 Forumite
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    They may move but the micro switch maybe faulty and leave 240 on the switch wire which is causing the boiler to fire. The valves are shut so the heat has now where to go and the boiler will cycle the pump to get rid of the heat.

    Get a heating guy to test for power on the orange wire from the zone valves in the wiring centre with no demand they should both be dead but I'd guess 1 of the cables will have 240 on it.
  • Jj_472
    Jj_472 Posts: 5 Forumite
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    Hi Alex, thank you for the help. I removed the orange wire from the heating zone valve and the motor stopped and never turned back on. When reconnecting it the boiler fired up and continued to run in the broken pattern.

    I have bought a new Drayton zone valve and replaced this and wired it in. Tested and now the boiler is shutting off correctly and not firing up on a cycle!

    Thanks for your help, I would not have thought of the zone valve otherwise as this one was only 4mo the old!!

    Cheers
    James
  • Alex1983
    Alex1983 Posts: 958 Forumite
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    Glad it's fixed, if it's only 4 months old you should be able to get the cost back under warranty.
  • Jj_472
    Jj_472 Posts: 5 Forumite
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    Ooh no!! The problem ha already happened again!!
    The heating and hot water is off but the boiler still starts up! I have disconnected the Drayton zone valve and water is dropping out of it. There must be a leak on the valve. Is this easy for me to replace or is a plumber needed?
    Many thanks!!
  • Le_Kirk
    Le_Kirk Posts: 22,353 Forumite
    First Anniversary First Post Photogenic Name Dropper
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    When you say the boiler starts up, does it ignite or is it just the pump running? If it is just the pump, I would look at the return pipe thermocouple. On my boiler it is clipped to the return pipe just before it feeds into the heat exchanger. It could be faulty or loose connection.
  • Alex1983
    Alex1983 Posts: 958 Forumite
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    You have a pressurised system so empty the system so the pressure shows 0 and then you can undo the nuts without leaking to much water and without fully draining the system. The vavle will have a and b stamped underneath make sure the new one goes the same way round.
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