Posting a message to the forum will remove the above advertisement
  1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.
  2. Checkout our Plumbers Insurance area - heavily discounted Public Liability Insurance and Van Insurance specifically designed for plumbers.

Discuss Timer replacement on a y plan system in the Central Heating Forum area at UKPlumbersForums.co.uk.

  1. jaydebruyne

    jaydebruyne Plumber GSR

    So went to a job today, replaced an old Randall 130 mechanical timer with a Honeywell st9400c on a y-plan system.

    Water channel fine. Heating channel was fine in that it sent a signal (if the room stat was calling) to the 3 port, but nothing on SL. Figured a faulty head. Replaced the head and same thing. So took off the head and manually moved the paddle and seems free as a bird.

    I’ve said to the custard I need to drain down and replace the entire valve as I don’t think it’s pushing far enough to make the connection.

    Thing is, when demand is on heating and the actuator kicks in, I can hear the micro switch click at the end (unless it’s the spring I can hear but I doubt it), but still nothing on SL.

    Am I missing something obvious here? (Can you hear the 2nd guessing???)
     
  2. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    so you have 240 on heating calling and hot water (seperately) ?
     
  3. jaydebruyne

    jaydebruyne Plumber GSR

    I have 240 coming from the thermostat to the white on the 3 port when heating is in demand, nothing on water if not in demand.
     
  4. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    Same with water and nothing on the heating ?
     
  5. jaydebruyne

    jaydebruyne Plumber GSR

    Didn’t check that..
     
  6. jaydebruyne

    jaydebruyne Plumber GSR

    But if I’m getting 240 on the white and the actuators moving over why wouldn’t that send 240 to SL (orange)? Unless the paddle isn’t moving over enough to make the connection..
     
    Last edited: Oct 6, 2018
  7. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    Correct doesn't need much for it to not contact
     
    • Like Like x 1
  8. jaydebruyne

    jaydebruyne Plumber GSR

    Looks like I’m draining down then Cheers Shaun
     
  9. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    S plan it
     
  10. jaydebruyne

    jaydebruyne Plumber GSR

    Think they’re gonna convert to a Combi so no point.. but I’ll give them the option..
     
    • Like Like x 2
  11. doitmyself

    doitmyself Well-Known Member

    If you are talking about CH only, there needs to be 240V on the grey wire (from HW thermostat Sat/Programmer HW Off) as well as 240V on the white wire from room stat.

    In mid-position (CH and HW) the boiler gets its SL directly from the HW thermostat, not via the orange wire.
     
    • Like Like x 1
  12. jaydebruyne

    jaydebruyne Plumber GSR

    Stupid f***ing 3 ports :D I wondered if that was needed but thought if the actuator was in operation after getting 240 on the white it would make the connection..
     
Loading...
Similar Threads - Timer replacement plan Forum Date
Hot water and heating timer Plumbing Forum Nov 19, 2018
Timer issue, Worcester boiler Central Heating Forum Nov 12, 2018