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Baxi combi 105 HE - Swtichmaster SM300 upgrade to Salus RT510RF

Discussion in 'Electrics UK' started by John34ssj, 1 Nov 2018.

  1. John34ssj

    John34ssj

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    Hello everyone,

    I've got an issue with my current thermostat Swtichmaster SM300 when on it buzzes like hell and setting the timer is just terrible.

    I want to upgrade to a Salus RT510RF but I just wasn't too sure about all the wiring and wanted to double check.
    By the thermostat controller there is the fused switch which controls the power to the boiler:
    [​IMG]

    Below the boiler there is a box that has 2 wires coming in and 2 coming out to the boiler:
    [​IMG]

    After taking off the boiler cover it seems that one cable is the mains supply and the other one is from the thermostat controller:
    [​IMG]

    The boiler schematics are shown below:
    [​IMG]

    And the thermostat I want to fit has the following:
    [​IMG]

    My question is would I wire up the thermostat as shown in top diagram - 1 Low voltage or 2 as 230v switching? Also could I power the thermostat controller box from the same box that is powering the boiler?

    Thank you :)
     
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  3. ericmark

    ericmark

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    I would wire as volt free, the two wires which switch the boiler on/off go to a reset selector switch, to try and use a common line could by-pass the switch. So use the Low Voltage diagram.

    Very confusing labels I will agree, normally called volt free and non volt free, as 230 volt is technically low voltage except in USA.
     
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  4. John34ssj

    John34ssj

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    Thanks. So if I am right this should be how the new schematic should look like?
    [​IMG]

    I unplug the old thermostat wires and pass the 2 wires to the new thermostat. And the from the main power I pass it through to the new thermostat.
     
  5. John34ssj

    John34ssj

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    Since I now know to use the low voltage wiring. I am still not sure if I can also run the thermostats controller box from the same mains cables as are powering the boiler itself?
     
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  7. flameport

    flameport

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    Not only can - you must. A single isolator is required for the boiler and any controls - not acceptable to have multiple supplies.
     
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  8. Walsden Boiler

    Walsden Boiler

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    Hi John, your diagram is helpful but the wiring in the photo is different from the diagram, the live and neutral are the other way around, can you tell me which one is the correct one please. Many thanks
     
  9. EFLImpudence

    EFLImpudence

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    If you mean these wires -

    upload_2019-12-14_21-38-31.png

    I would wire as in the diagram.

    It doesn't matter for function.
    It's live and switched live(not neutral) so the blue should be sleeved brown.
     
  10. Walsden Boiler

    Walsden Boiler

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    Many thanks :)
     
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