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Discuss Pump staying on at night. Faulty PCB relay or HPA2 m/switch - or ? in the Central Heating Forum area at UKPlumbersForums.co.uk.

  1. Dmitri

    Dmitri New Member

    Glowworm Ultimate 50FF + 2x Danfoss HPA2 valves for CH and HW.
    Pressurised system. No frost stat and wiring (S-plan – I think) has been OKd by two separate engineers.

    At the end of the day, the pump is not switching off when boiler/CH/HW shut down.
    After the 6-7 minute pump overrun, the levers on the HPA2 are in the closed position but the pump remains on for hours. This tends to happen more when the whole system is hot and has been running all day.

    If I switch off the pump via mains power at bedtime, and switch it back on in the morning the pump comes on even though the boiler cabinet is cold and the controller (Honeywell ST699) is not calling for heat. The boiler fires up when I switch the CH on.

    If I then let the boiler run for about 1 minute – or an hour, and then switch off the CH, the boiler shuts down, the pump overrun occurs and the pump stops as normal.

    The boiler ia 20 years old, has had several HPA2s and 3 (4?) PCBs. It had a new stat and PCB two years ago and a new top fan a month ago.

    Could my problem be a faulty micro-switch on the CH (or HW) motorized valve after a prolonged period of heating or – as has been suggested - a faulty relay on the PCB? (but there are no noises coming from the control box). Or something else?

    Any advice would be much appreciated
     
  2. AMGasServices

    AMGasServices GSR

    I don’t think it’s your PCB. It’s possibly one of your valves or programmer.
     
  3. DGT plumbing

    DGT plumbing GSR

    Is your pump controlled by your boiler or is it directly wired into the control wiring centre. If it's your boiler there could be an internal problem with that. If it's into the wiring centre you need to test your switch lives from your control valves to see if either of them are calling when they are off. Hard to say definitively without seeing it in the flesh. So many options to go wrong.
     
  4. Murdoch

    Murdoch Active Member

    Contributing as a spark ... I would doubt its the valve as this should send the signal to run the boiler ... not just to the pump to run

    Is the pump internal or external to the boiler?
     
    • Agree Agree x 2
  5. Dmitri

    Dmitri New Member

    Thanks for these two replies. Not sure of answer to 'is pump wired to control centre of boiler'. Looking at the wiring diagram in the Glowworm manual, the pump live is connected to one end of a fuse on the PCB so I possibly need to test the switch lives. Wouldn't harm to check this anyway.
     
  6. Dmitri

    Dmitri New Member

    Thanks Murdoch - pump is external to boiler. Pretty sure its just the pump that runs and not the boiler as well.
     
  7. Murdoch

    Murdoch Active Member

    Where is the pump wiring going to / from? The boiler or wiring centre?

    What test equipment do you have?
     
  8. DGT plumbing

    DGT plumbing GSR

    If the boiler is controlling the pump then it's going to be something internal to the boiler that's telling it to run so your going to need to get yourself a gas safe engineer.
     
  9. Steve weightman

    Steve weightman GSR

    Had several from experience it's the pcb otherwise the boiler would fire up It's a motorised valve
     
  10. Harvest Fields

    Harvest Fields S. Mod Trusted Plumber GSR Top Contributor!!

    • Agree Agree x 1
  11. Steve weightman

    Steve weightman GSR

  12. Steve weightman

    Steve weightman GSR

    And how thanks
     
  13. Harvest Fields

    Harvest Fields S. Mod Trusted Plumber GSR Top Contributor!!

    Click on one of the 3 names and start conversation
     
  14. garygvl

    garygvl GSR

    pump external but overrun controlled by pcb
     
  15. Dmitri

    Dmitri New Member

    Wiring.JPG
     
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