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wiring vaillant ecotec plus 637

Discussion in 'Electrics UK' started by google, 2 May 2019.

  1. google

    google

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    Hi everyone
    I need help wiring up a Vaillant system 637 ecotec
    shall I just follow Honeywell s plan as shown below

    upload_2019-5-2_20-19-7.png
     
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  3. AndyPRK

    AndyPRK

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    I have a similar model IIRC. (well 18 years old lol)

    So the supply goes direct to the boiler (so it can run the fan when it wants, and frost protection).
    Then there must be a trigger wire to the boiler from the orange or grey wires from the valves.
    Pump is inside the boiler on mine, so don't need to worry about that.

    Mine was on Y plan but now S
     
  4. google

    google

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    do you mean the L cable from the boiler terminal has to terminate into orange wire in the wiring centre !
    thanks
     
  5. flameport

    flameport

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    Not entirely.
    The pump is integral to the boiler.
    Boiler requires a permanent supply L,N,E from terminals 1,2,3 and an additional SL from terminal 10.

    The rest is as shown, if you really are intending to have a separate timer and room thermostat in the style of the last century.
     
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  7. google

    google

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    thanks for your help but I looked at the PCB there is no terminal for SL please see the attached photo
     

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  8. flameport

    flameport

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    Control input is the 230V RT on that one - it's all in the installation instructions.
     
  9. Johnmdc

    Johnmdc

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    And don't forget to remove the red link wire in the 24V RT terminals or the boiler will run constantly.
     
  10. ericmark

    ericmark

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    S-Plan-newc.jpg I would guess some modification will be required with a modulating boiler, the thermostat should not turn boiler off/on but up/down yet the timer will still turn boiler off/on, so the thermostat will not be connected to the motorised valve as in old system but direct to boiler.

    I have questioned without getting a good answer how one uses a S plan to control upper and lower floors when you only have the option to fit one modulating thermostat, as far as I can see one has to use electronic heads on the TRV and get rid of the S Plan as there is no provision to use modulating thermostats with the S plan, or control lower floor only.

    It seems government is behind the times, insisting on split heating control when we have passed that point with technology, even the boiler manufacturers seem to be lagging behind, Vaillant I thing supports OpenTherm so likes of Tado and EvoHome can be used, but Bosch only have their own "Wave" thermostat which will only measure and control one room.

    Will your system as you show work, yes it will, will it work with maximum efficiency, I don't know, theory and practice do not seem to match, all down to air movement, what doors are fitted, how much heat the walls store, so in my case the electronic head turned radiator off, but it was already full of hot water by that time, so room over shot the mark, fiddling with lock shield valves improved it, the TRV is bi-directional, however if not fitted to supply side radiator over shoots.

    I have given up, moving house, new house is oil, so although modulating boiler 18 to 24 kW is really a laugh, so returning to old system.
     
  11. DIYnot Local

    DIYnot Local

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