S Plan, C plan or Y plan?

Discussion in 'Plumbers' Talk' started by oliver1234, Mar 29, 2008.

  1. oliver1234

    oliver1234 New Member

    I am trying to sort a heating problem for a freind and I suspect that there may be a wiring problem. Her setup is as follows: Flow from boiler to cylinder cupboard then in to pump. From pump to a 22mm T, one side of the T goes to the cylinder heating coil other side of the T goes to heating flow but via a zone valve.

    Most of the diagrams I have seen have either a 3 port valve of 2 zone valves so I'm a but stuck and I don't know which wiring diagram to refer to.

    She also has a cylinder stat and room stat.

    Also what position do zone valves default to? I'm assuming that when power is removed they close, is this correct?

    Thanks chaps.
  2. oliver1234

    oliver1234 New Member

  3. HOTDOG ø

    HOTDOG ø Active Member

  4. tomplum

    tomplum Active Member

    hi olie
    what you have there is a basterdized plan, when the water only is on, the cylinder stat will knock off the boiler and pump, when in heating mode the live to the boiler and pump will not go throu the cylindr stat so it will work but the water will overheat, in default the valve will close, they have probably just used the brown wire in the valve to acuate it and the blue and earth and ignored the orange and grey,
    the best solution is to upgrade it to a s plan, all the elementes are there exept the valve,
  5. oliver1234

    oliver1234 New Member

    Thanks for the replies chaps, I suspected that the hot water would have no real control becuase I couldn't see a way in which the flow to the cylinder is controlled during heating only.

    I think with the diagram that Hotdog has posted I will be able to get it working but will recommend she buys another zone valve or a three port.

    Thanks again to you both!
  6. bloop the gasman

    bloop the gasman New Member

    Hi There, I've seen a few like this. The system is wired for "hot water priority" ie on demand for hw and c/h the boiler fires and the zone valve stays shut until the cylinder stat is satified. then it sends a live to the zone valve which opens. causes a 30 /40 minute delay until the rads start to heat. The last one I saw the rads would not get hot at all, found the strap holding the cylinder stat had rotted and the stat was on the floor next to the cylinder, repaired job with a curtain wire :)
  7. rome60

    rome60 New Member

    OLiver,yes convert to S plan if your progammer is nekt to boiler downstairs which should be 2 channel,you will need to get a 4core back to it.Gasman is probably right check wiring back from cyl stat to the wiring centre see if brown or orange are connected to cyl stat common.
  8. Dick Puller

    Dick Puller New Member

    Another system that's quite like that was used by installers using the old ACL controls............The programmer was used like a gravity system, so you couldn't select CH only, the HW temperature was only controlled by the boiler stat & a room stat controlled the zone valve. I always thought it a bit daft, when you could easily incorperate a second zone valve, create an 'S' plan & have a much more economic system.
  9. Ash_vale

    Ash_vale New Member

    This might help people

  10. sam spade

    sam spade Active Member

    Not now, it won't. It's 11 years too late.[/QUOTE]
    The Teach likes this.
  11. The Teach

    The Teach Well-Known Member

    so much has changed in 11 years, may be Ash vale can publish some nest,wiser,hive,tado (udders are available) instructions. loads of people buy the mentioned equipment and think its a diy install.

  12. sam spade

    sam spade Active Member

    Good Idea; but as separate post(s) - not here!

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