New Thermostatic Shower Valve Not Working - No flow

Discussion in 'Plumbers' Talk' started by Os11art, Dec 9, 2022.

  1. Os11art

    Os11art New Member

    Just had a new thermostatic gravity fed shower installed.
    We are struggling to get any flow from the main shower head.
    We have a 2.0Bar showermate pump installed also.

    Its a 3-way valve with a diverter, so 3 controls:
    1. Main shower on/off
    2. Temperature control
    3. Divertor to hand shower/body jets/off

    We always get flow from the divertor hand shower head but not the main rainfall shower.

    Anyone have any ideas?

    thanks
     

    Attached Files:

  2. CGN

    CGN Screwfix Select

    Could be an air lock
     
  3. Mike83

    Mike83 Screwfix Select

    Probably not enough flow to activate the pump from the rainfall.
    If you lift the handheld above the rainfall and turn on the shower does it still work?
     
  4. Os11art

    Os11art New Member

    Just lifted the handheld above the rainfall and the handheld still worked.
     
  5. Mike83

    Mike83 Screwfix Select

    Do you get any flow at all from the rainfall?
     
  6. Mike83

    Mike83 Screwfix Select

    Try running the handheld as normal then as fast as you can divert to the rainfall.
    Hopefully the pump doesn’t turn off.
    Does it then work?
     
  7. Os11art

    Os11art New Member

    Yeah we get flow once the handheld has been operated then we switch to operating the rainfall lever and it kicks in.
    Sometimes the rainfall works but mostly when turning the lever it doesn’t.
     
  8. Os11art

    Os11art New Member

    Yes that’s how we are currently getting round the problem
     
  9. Mike83

    Mike83 Screwfix Select

    Probably need a different pump then.
    Others on here can give better advice than me though.
     
    Os11art likes this.
  10. terrymac

    terrymac Screwfix Select

    Do you mean after the hand held triggers the pump ,the rain head SOMETIMES still doesn't give water while the pump is still running ?
     
  11. Os11art

    Os11art New Member

    No sorry once the handheld has activated the pump the rainfall will always kick in and work
     
  12. terrymac

    terrymac Screwfix Select

    Ok ,fine. It's a flow issue ,or rather a lack of it to trigger the pump due to low gravity pressure.
    Wasn't a negative head pump installed ???
    You should take issue with the installers.
     
  13. Os11art

    Os11art New Member

    I believe it’s a positive head like attached, same model.
     

    Attached Files:

  14. Os11art

    Os11art New Member

    We live in a bungalow with gravity fed tank in loft and positive head pump installed.
     
  15. Mike83

    Mike83 Screwfix Select

    You probably have a slight head of water but it’s just not enough to trigger the pump.
    Negative head pump should solve it.
     
  16. Os11art

    Os11art New Member

    This is the position of the pump
     

    Attached Files:

  17. Os11art

    Os11art New Member

    The rainfall seems to work when the temperature is set to cold. Our cold supply pressure is a lot greater than the hot. would this confirm it’s a supply pressure issue?
     
  18. dcox

    dcox Screwfix Select

    The pressures should be similar. Perhaps the cold is mains - should be from your CWST with a dedicated feed.

    Try turning your main stop tap off and retry the shower on cold. If it doesn’t run, it’s been incorrectly plumbed.
     
  19. Os11art

    Os11art New Member

    Yeah it has a dedicated feed from the cold water tank.
     

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