Buzzing 3-port Valves

Discussion in 'Plumbers' Talk' started by Jimbo, Mar 23, 2021.

  1. Jimbo

    Jimbo Screwfix Select

    I'm not having much luck with 3-port diverter valves (fitted in correct orientation).

    Valve 1 - Motor dead, changed on install
    Valve 2 - loud clunk when moving, buzzed also, changed after a couple of months
    Valve 3 - did not seal in either position, but silent, changed after a couple of weeks
    Valve 4 - works fine but buzzes loudly, resonating through water cylinder (can feel the pipes vibrating)

    Valve 4 is a Honeywell so I was hoping this would be fixed. Any ideas what's causing this buzz or how to resolve?
  2. quasar9

    quasar9 Screwfix Select

    Motors on 3port valves are powered on when thermostat(s) call for heat, and effectively stalled when at the end of their travel. Therefore a 50Hz buzz is always there, although guessing your pipework is resonating making it sound louder. Perhaps a few more clips on the pipe work or damping down with some rubber tape/mastic may help !
  3. kiaora

    kiaora Guest

    to avoid confusion. do you have 4 x 3 port valves on your system ?

    or 4 x 2 port? zone valves
  4. Jimbo

    Jimbo Screwfix Select

    One 3-port diverter valve, it has just been replaced 3 times and still not satisfactory.
  5. kiaora

    kiaora Guest

    ah i see

    when the system is in hot water only, the valve is at rest, no power driving the motor

    the rest position is hot water, port B on the valve. port A to heating

    so when hot water on, no valve action, just switched live to boiler via cylinder stat.

    are you getting any buzzing at the valve in hot water only,? if so, its an installation or wiring fault

  6. Jimbo

    Jimbo Screwfix Select

    In this case A is DHW - it's connected to a heat pump so this reduces the energy use by the valve since the CH run hours are far longer. But yes, buzzing only when motor active i.e. flow to port A.
  7. kiaora

    kiaora Guest

    Interesting, with heating on, is it wired to go to mid position when hot water call ? Or fully over ?
    Normally 2 live wires are required to hold it fully over ? The grey and the white ?

    just interested how it was wired ?
  8. Jimbo

    Jimbo Screwfix Select

    Its a diverter so it's literally L-N-E connection, when energised it flows AB->A and when not energised it flows AB->B.
  9. MGW

    MGW Screwfix Select

    Can't see how a three port with centre position I.e. Y Plan not W Plan will ever not emit some sound.

    Lucky I only have two port valves, as only type AC RCD fitted, need type A with three port valve.

    My heating I hear sounds all of the time, be it a TRV opening or closing or boiler running, or Myson fan assisted radiator cutting in, never found it a problem.

    My dad never had a problem, he worked in a power station and was deaf to 50 Hz.
  10. MGW

    MGW Screwfix Select

    Sorry did not realise W Plan. Have you got right valve.

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