Y-plan with Potterton Suprima boiler problem.

Discussion in 'Plumbing and Central Heating' started by skywatch99, 13 Oct 2019.

  1. skywatch99


    30 Mar 2012
    Thanks Received:
    United Kingdom
    The boiler was taking some time to come on after a call for heat and then a few weeks ago I came home to a really hot house as the heating had been running all day! Boiling radiators and hot water in the tank.

    The room stat was satisfied so it should not have been running at all (the water is only on 2 hours a day, one in the morning and one in the evening). Tuening off call for heat from CH and HW at the controller did not stop it running. I had to power off everything.

    A heating engineer came out and said it was a control board problem. Then board has since been replaced and whilst the boiler now starts quickly when a call for heat comes in, it went into full on mode again yesterday. The DV was in mid position.

    Could this be a problem with the diverter valve microswitches?
    Maybe the latching relay in the room stat sometimes sticking?
    What else can it be? The overheat and thermister in the boiler all tested OK when the engineer was here.

    Thanks for any hints or help on getting to the cause of this!
    Last edited: 13 Oct 2019
  2. Sponsored Links
  3. ericmark


    27 Jan 2008
    Thanks Received:
    Llanfair Caereinion, Nr Welshpool
    United Kingdom
    The valve is complex John Ward does a really good video.
    mid-position-valve.jpg Mid position means the white is energised and grey is not, so if grey not energised then the tank thermostat must be calling for heat, so it is possible a back feed from the orange is holding valve open, so I would be looking at the tank thermostat if it was mine.

    However only ever worked on one Y Plan so could be wrong.

    PS have you checked to see if the bleeding lever on motorised valve has not been left latched on?
    • Like Like x 1
  4. DIYnot Local

    DIYnot Local

    3 Sep 2019
    United Kingdom

    If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

    Select the supplier or trade you require, enter your location to begin your search.

    Are you a trade or supplier? You can create your listing free at DIYnot Local


Share This Page