Central heating on overnight

Discussion in 'Plumbers' Talk' started by Allan Thornton, Dec 3, 2019 at 8:28 PM.

  1. Allan Thornton

    Allan Thornton New Member

    Hi all since firing up the heating in October, it’s staying on overnight. I drained the system down to reposition the bathroom Radiator, and decided to change the pump as it was getting hot even when the pipework each side was warm, when I removed the pump it was badly scaled up. Both motorised valve have also been renewed with genuine Honeywell ones. I’ve also rewired the main junction box as the old one was broken and full of block terminals loose inside. The room stat is working fine but the the heating doesn’t go off via the programmer old Honeywell one.
    So I’m thinking the programmer is past its best or I’ve done something with the wiring, although I’ve checked it. The system is a conventional potterton boiler with 2 x 2 way motorised valves, room stat, cylinder stat and a basic Honeywell programmer. Any ideas please
     
  2. Mike83

    Mike83 Well-Known Member

    Did you alter any wiring behind the programmer?
    Are the times set correctly on the programmer?
    If you remove the programmer from the wall does the heating turn off?
    Do lights on the programmer light up when they shouldn’t?
     
  3. Allan Thornton

    Allan Thornton New Member

     
  4. Allan Thornton

    Allan Thornton New Member

    Hi Mike, I don’t think so, I’ve double checked the timings on the programmer. I’ll try removing the timer and just leave the back plate on the wall. The lights seem ok on the timer
     
  5. Mike83

    Mike83 Well-Known Member

    A multimeter or voltage tester would make this easier to diagnose if you have any available.
     
  6. Allan Thornton

    Allan Thornton New Member

    Yes I have a good multimeter to use
     
  7. Mike83

    Mike83 Well-Known Member

    When the heating and HW are both turned off are any of the browns on the 2 zone valves 230v.
     
  8. Allan Thornton

    Allan Thornton New Member

    I’ll have to check tomorrow as my meter is at work, I’ll try that test
     
  9. Mike83

    Mike83 Well-Known Member

    If the programmer is turned off or removed from the wall and either brown at the zone valves is live then it is probably wired incorrectly.
    If the permanent live at the zone valve (grey) and switched live (orange) are both live then either it’s wired wrong or one of the new zone valves are the issue.
     
  10. Allan Thornton

    Allan Thornton New Member

    With the programmer off the valve brown and orange are zero volts, but the grey is 240(permanent live)
    With the programmer on the results are the same
     
  11. Mike83

    Mike83 Well-Known Member

    That all sounds correct.
    Is the boiler and pump continuously running even with the programmer turned off
     
  12. Allan Thornton

    Allan Thornton New Member

    All working via the thermostats, boiler clicks in as normal when the room stat is turned up a tad even when the programmer is off
     
  13. Mike83

    Mike83 Well-Known Member

    Are you able to trace all the wiring
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  14. Allan Thornton

    Allan Thornton New Member

    I think I’ve found it with your help, the room stat red and programmer red we’re both connected to a live, so my bad when I changed the wiring box. Thanks for your advice and help, you’ve saved my bacon
     

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