Differential Bypass

Discussion in 'Plumbers' Talk' started by bathroom boy, Mar 16, 2010.

  1. bathroom boy

    bathroom boy New Member

    Posted the other day, leak on my sealed system, found an aav leaking sorted that but also bypass valve is leaking from thre control, only been in 2 years what a load of cack,do I really need it as the towel rad does not have a trv, will this suffice? Boiler is worcester 30cdi conventional.Cheers.
  2. solenoid

    solenoid New Member

    yes you do otherwise you will bugger up your pump when the x 2 port valves shut off!!!
  3. doing a bit

    doing a bit New Member

    is there a bypass on the boiler ?
  4. tomplum

    tomplum Active Member

    the energy effieciantcy nurds will tell you that there needs to be a differential bypass, but if you take the wheel head off the towel rail and put a lockshield head on so no one can turn it off, that will be ok for a practical fix,
  5. solenoid

    solenoid New Member

    thats ok for getting rid of heat from the boiler, but you still need a bypass just after the pump to bypass the valves. cos the pump when shut down will still pump for 45 seconds and that can mess up the motor if you don't!!
  6. Dick Puller

    Dick Puller New Member

    On an 'S' plan with two motorized vales, then a by-pass is required prior to the two MVs, if you don't have a by-pass on this type of system you will 'dead head' the circulator - as stated above. However, if your system is a 'Y' plan system with a 3 position motorized valve, you can do as Tom has stated above, or ensure there's a large radiator with no TRV fitted.
  7. Dick Puller

    Dick Puller New Member

    Sorry, I should have added; a by-pass is not required on a 'Y' plan system as there's always an open outlet port on the valve.
  8. bathroom boy

    bathroom boy New Member

    Thanks for the replies lads, Iv'e changed it with a honeywell unit, motto of the story, buy cheap, buy twice.

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