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Discuss 3 port valve override floppy - possible wiring problem? in the Central Heating Forum area at

  1. vtechnician

    vtechnician New Member

    Hi all, Im hoping one of you experts could shed some light on a potential issue.. but first a little background.

    In November 2016 I spent considerable money on a new boiler. The job involved:

    1) removing old conventional boiler (in kitchen). Remove F&E tank from attic.
    2) Install Valiant system boiler in attic.
    3) Install larger HW cylinder, grunfos pump, 3 port valve and Honeywell programmer in airing cupboard.
    4) install room stat in downstairs hallway.

    Everything seems to be working as it should however when I set the HW and CH to the "off" setting on the programmer, should the lever on the 3 port valve remain floppy? (Note room stat turned down also).

    When there's only HW demand, i hear the motor in the valve operate and the lever has resistance.

    If i turn the power off to the boiler/programmer. I hear the 3P valve return to its starting position and the lever has resistance. When i turn the boiler back on the lever has resistance until there's CH demand and then it remains floppy.

    Im no expert by any stretch of the imagination but this doesn't sound right to me. I understand that this boiler pumps water around the rads for a few minutes after turning off to cool the heat exchanger. The pump turns off after a few minutes. Could it be the 3 port valve isn't receiving the signal to turn off also?
  2. joni os

    joni os Plumber

    With no call for HW or CH valve remains in previous position. if CH on to CH off is last call, lever floppy. HW on to HW off last call, lever will show resistance. All power off valve closes.
    Last edited: Jan 22, 2017
  3. vtechnician

    vtechnician New Member

    thanks Joni. sounds like its working as it should.
  4. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    did you go for an unvented cylinder (mains pressure hot water)?
  5. joni os

    joni os Plumber

    Hopefully, not with a 3 port, but question worth asking.
  6. joni os

    joni os Plumber

    Hopefully, not with a 3 port, but question worth asking.
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