1. Visiting from the US? Why not try DIYnot.US instead? Click here to continue to DIYnot.US.
    Dismiss Notice

Y Plan + 2 port valve wiring

Discussion in 'Plumbing and Central Heating' started by AndyPRK, 12 Jul 2018.

  1. AndyPRK

    AndyPRK

    Joined:
    4 Jan 2009
    Messages:
    5,880
    Thanks Received:
    593
    Location:
    Herefordshire
    Country:
    United Kingdom
    Could someone please tell me the standard way to wire in this new requirement 2 port valve into a Y plan system please.


    What is the plumbing alternative to not fitting one?

    Thank you
     
  2. Sponsored Links
  3. muggles

    muggles

    Joined:
    28 Oct 2005
    Messages:
    13,332
    Thanks Received:
    3,072
    Location:
    Daventry
    Country:
    United Kingdom
    Eh? What are you trying to achieve?
     
  4. AndyPRK

    AndyPRK

    Joined:
    4 Jan 2009
    Messages:
    5,880
    Thanks Received:
    593
    Location:
    Herefordshire
    Country:
    United Kingdom
    Plumber wants to fit an additional 2 port value due ti new regulations.

    I would like to see how it's wired in.
     
  5. stem

    stem

    Joined:
    20 Jul 2005
    Messages:
    6,761
    Thanks Received:
    1,601
    Location:
    Nottinghamshire
    Country:
    United Kingdom
    A 'Y' plan system has a 3-port valve, which can only close off one outlet port at a time, meaning there is always one outlet port open.

    If you then add an additional 2-port valve, when that valve opens for whatever it is supplying (you haven't told us what that is) and it switches the pump & boiler on, one of the outlet ports fed by the 3-port valve will also allow water to flow through it whether it is required or not. So, using a combination of 3-port and 2-port valves on the same system doesn't work. For multiple zones you would need an S-Plan.

    So as muggles says, you need to explain what you are trying to achieve with this additional valve.

    What regulations are you referring to?
     
    • Thanks Thanks x 1
  6. picasso

    picasso

    Joined:
    8 Apr 2008
    Messages:
    10,626
    Thanks Received:
    2,665
    Location:
    Essex
    Country:
    United Kingdom
    Last edited: 12 Jul 2018
  7. AndyPRK

    AndyPRK

    Joined:
    4 Jan 2009
    Messages:
    5,880
    Thanks Received:
    593
    Location:
    Herefordshire
    Country:
    United Kingdom
    I'm having an unvented cylinder replaced with another due to leak.

    I assume the 2 port goes to the HW but you tell me what the new method is :)
     
  8. stem

    stem

    Joined:
    20 Jul 2005
    Messages:
    6,761
    Thanks Received:
    1,601
    Location:
    Nottinghamshire
    Country:
    United Kingdom
    Ah good, some useful information at last. Based on your previous information (and probably because I have done one or two recently) I thought that you were splitting your upstairs and downstairs heating into two zones to meet the new building regulations. However now you have explained what you are doing, AndyPRK is quite correct.
     
  9. muggles

    muggles

    Joined:
    28 Oct 2005
    Messages:
    13,332
    Thanks Received:
    3,072
    Location:
    Daventry
    Country:
    United Kingdom
    Ah, got there in the end. Yes, the 2-port goes on the flow to the cylinder. You need a G3-Registered installer to fit the cylinder for you and register the installation with Building Control, it's not a DIY job. A competent installer will know how to wire it up correctly
     
  10. Sponsored Links
  11. AndyPRK

    AndyPRK

    Joined:
    4 Jan 2009
    Messages:
    5,880
    Thanks Received:
    593
    Location:
    Herefordshire
    Country:
    United Kingdom
    Yeah the only snag is that I modified the standard wiring a few years ago, so I would like to understand if the 2 port valve will work with my modified system or whether I need to convert it back. Trying to avoid giving the poor plumber a head ache
     
  12. AndyPRK

    AndyPRK

    Joined:
    4 Jan 2009
    Messages:
    5,880
    Thanks Received:
    593
    Location:
    Herefordshire
    Country:
    United Kingdom
  13. picasso

    picasso

    Joined:
    8 Apr 2008
    Messages:
    10,626
    Thanks Received:
    2,665
    Location:
    Essex
    Country:
    United Kingdom
    There is a diagram on page 22 showing how to wire up a 3 port and a 2 port.
     
    • Thanks Thanks x 1
  14. AndyPRK

    AndyPRK

    Joined:
    4 Jan 2009
    Messages:
    5,880
    Thanks Received:
    593
    Location:
    Herefordshire
    Country:
    United Kingdom
    picasso or anyone. Could you please explain the requirement for this additional valve?

    Would just like to know what they were trying to achieve?

    Thank you
     
  15. flameport

    flameport

    Joined:
    10 Mar 2007
    Messages:
    9,909
    Thanks Received:
    1,985
    Location:
    Poole, Dorset
    Country:
    United Kingdom
    Prevents water flowing to heat the cylinder in the event of various failures. A standard 2 port valve will be closed due to a spring inside if power is removed or the valve motor fails.

    Can't be done using a Y / 3 port valve as that defaults to HW open which could result in the cylinder being overheated.
     
    • Like Like x 1
  16. MeldrewsMate

    MeldrewsMate

    Joined:
    27 Jan 2010
    Messages:
    1,064
    Thanks Received:
    265
    Location:
    Buckinghamshire, Darn Sarf
    Country:
    United Kingdom
    It's to isolate the heat input to the hot water cylinder. It means that the valve will fail to its closed position and stop the cylinder from overheating. I suppose the G3 regs people wanted to avoid overheating if a solid fuel heat source is used.
     
  17. AndyPRK

    AndyPRK

    Joined:
    4 Jan 2009
    Messages:
    5,880
    Thanks Received:
    593
    Location:
    Herefordshire
    Country:
    United Kingdom
    So if the thermostat in the cylinder fails its still no help.

    If the boiler decides to keep going (when not requested) this new valve will help. Somewhat unlikely failure mode.
     
Loading...

Share This Page