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Luke Warm Water all the Time

Discussion in 'Plumbing and Central Heating' started by Caesar, 2 May 2020.

  1. Caesar

    Caesar

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    Hi All

    I have a problem in that the central heating system even when turned to hot water only produces just luke warm water for the shower even if it is turned for a few hours!

    The system is Valiant Boiler conventional system and is a sealed system. What is unusual is that downstairs radiators remain cold when hot water is called for but upstairs radiators warm up.

    Am i right in thinking this could be a 3 port valve problem? I know that the port is 22mm Honeywell 3 port Valve only replaced 3 years ago!

    Any help would be greatly appreciated.

    Many Thanks

    Caesar
     
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  3. easyflow

    easyflow

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    You are right to think its a 3 port valve, the fact its only 3 yrs old don,t matter, check the wiring is in order.
    Should be a lever on the valve that enables you to open it manually to get hot water if it packs up.
     
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  4. flameport

    flameport

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    3 port valves are open to the hot water cylinder by default, so if the radiators are heating then either the valve has physically jammed in the heating position, or there is a wiring problem.

    With HW only selected, the valve should not receive any power on either grey or white wires.
     
  5. Caesar

    Caesar

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    Hi Easyflow / Flameport

    Thanks for your replies and pointing me in the right direction. Could the synchron motor be at fault? If so any way to test the 3 Port Valve and if so what is the procedure etc?

    Many Thanks
     
  6. pete50

    pete50

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    My same symptoms were caused by an air lock in the coil. I changed the complete motorised valve and it was still the same. I then fitted a bleeder to the coil feed pipe and BINGO hot water again. I don't know whether your actuator has an indicator but if it has and its pointing to water when you only have the hot water on then if you are not getting hot water it can only be the valve or an air lock. Mine was an airlock.
     
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  8. flameport

    flameport

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    No. If it was, the valve would be permanently at hot water only and the heating would never work.

    Test voltage at the wiring centre on the actuator grey wire and the white wire. Voltages should be:
    HW only = grey 0v, white 0v
    Heating & HW = grey 0V, white 240V
    Heating only = grey 240V, white 240V.
    Nothing selected = grey 240V, white 0v
    If any of those are wrong, there is a wiring problem or the programmer/timer/other is defective.

    If those are correct, remove the actuator from the valve, and see if the spindle can be turned by hand - it should move easily. If not, the valve has seized.
     
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  9. Chris_W

    Chris_W

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    Could it not fail in ch then? I was led to believe that it stays in last known setting?
     
  10. flameport

    flameport

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    Grey only will hold the valve at CH only if it was already there.
    Without any power, the default is always HW only, and if HW is requested, grey is disconnected.
     
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  11. Chris_W

    Chris_W

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    So basically, if the grey loses the 230vac, then it springs back?
     
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