No hot water without heating

Discussion in 'Plumbers' Talk' started by breezy, Sep 13, 2021.

  1. breezy

    breezy New Member

    Worcester System boiler with unvented cylinder.

    Seems to function fine when the heating is on, but as soon as you turn the heating off the cylinder is no longer heated.

    The Danfoss HPA2 motorised valve to the cylinder coil seems to work/move across to open the valve. Could it be the the microswitch inside has failed which is no longer triggering the boiler to fire?
     
  2. terrymac

    terrymac Screwfix Select

    Quite possible . When you say it seems to work ,what do you mean ,it works manually ,or it does actually move electrically ?
     
    breezy likes this.
  3. breezy

    breezy New Member

    It will move across/rotate when the thermostat on the tank is adjusted up/down. i.e. it's opening the flow of water, but isn't getting the boiler to fire.
     
  4. terrymac

    terrymac Screwfix Select

    Microswitch or wiring issue ,probably the former.
    Check the wiring centre for loose connections ,if all good,fit a new actuator
     
  5. breezy

    breezy New Member

    Perfect, thank you - that's very reassuring.

    Is there a wiring diagram somewhere for them so I can check the voltages on the terminals in the wiring centre?
     
  6. terrymac

    terrymac Screwfix Select

    Plenty of wiring diagrams on the internet . The orange is the switched live to fire the boiler.
     
  7. breezy

    breezy New Member

    I tested the voltages on the orange wire today. When closed, 70v. When open and calling for heat, 240v.

    Seems the micro switch is working as it should….
     
  8. terrymac

    terrymac Screwfix Select

    Show us a pic of the wiring centre.
    Did you measure voltages at the wiring centre ?
     
  9. breezy

    breezy New Member

    I did yes.

    Here's a photo for you.... IMG_8102.jpg
     
  10. Mike83

    Mike83 Screwfix Select

    The oranges should both be in the same terminal.
    I’m guessing the orange wire that belongs to the heating valve is in the correct terminal.
     
    breezy likes this.
  11. breezy

    breezy New Member

    Thank you. That's helpful to know.

    The orange in 12 is the CH
    The orange in 7 is HW
     
  12. Mike83

    Mike83 Screwfix Select

    Actually if you move any orange wire that would leave a black wire itself.
    Looks like the 2 oranges and 2 blacks should be together
     
  13. terrymac

    terrymac Screwfix Select

    Wired incorrectly ,when did system stop working right ?
     
  14. Mike83

    Mike83 Screwfix Select

    So move the red link piece in 6 over to 7
     
  15. breezy

    breezy New Member

    I found this article in the manual for the terminal box. The wire colours don't seem to correspond with the colours as wired up in my box. As you say, both oranges seem connected together in the manual too.

    Rotated photo of my terminal box and rotated it to show the same orientation as the manual. IMG_8101.jpg IMG_8102.jpg
     
  16. breezy

    breezy New Member

    Just bought the house so it's all new to me. Haven't moved in yet but I found I had to use the electric immersion heater to warm the water instead of the gas boiler.
     
  17. Mike83

    Mike83 Screwfix Select

    Someone’s definitely been messing with that wiring.
     
  18. terrymac

    terrymac Screwfix Select

    As Mike said both orange switched lives should be in the same terminal,move the red link wire as he advised.
     
  19. terrymac

    terrymac Screwfix Select

    Definitely !
     
  20. Mike83

    Mike83 Screwfix Select

    There will obviously be a black wire connected with the oranges that probably serves no purpose.
    As you have a system boiler the oranges would usually only tie in with 1 other wire. It won’t cause any issues though as your not really changing that anyway.
     

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