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Upgrading thermostat

Discussion in 'Electrics UK' started by Zooropa68, 12 Sep 2021.

  1. Zooropa68

    Zooropa68

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    Hi there, I'm upgrading my thermostat from salus rt310 to rt310rf, and want to make sure my wiring is correct. The Thermostat is connected to a 3 channel programmer.

    Inside the rt310 are 2 wires brown (live connected to COM), and a grey connected to NO. There is also an unconnected black wire inside - I wonder what that is for?

    Could someone have a look at schematic and confirm the correct wiring I need to follow.
    I think in the receiver I connect brown to L and COM, the grey to NO, would the black wire go to N?
     

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  3. EFLImpudence

    EFLImpudence

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    That is correct, BUT you will first need to make sure the Black is connected to neutral at the other end.
     
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  4. Zooropa68

    Zooropa68

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    Thanks, so if I get my multimeter and confirm black and grey are connected on continuity check then I'm good to go?
     
  5. EFLImpudence

    EFLImpudence

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    No. You must check the other end of the cable and connect the Black to a supply Neutral.
     
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  6. flameport

    flameport

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    One of those is a battery powered wired thermostat, the other is a battery powered wireless thermostat with a 230V wired receiver unit.
    The receiver is intended to be located out of sight, typically next to the boiler or similar. Not where an old thermostat was previously located.

    The existing thermostat will only have power when the programmer is on.
    Installing the receiver unit there will not work, as it requires power permanently.
     
  7. Zooropa68

    Zooropa68

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    The brown wire in it measures 240v

    The reason I want to change thermostat, is because it is in a large hallway next to a frontdoor, the temperature in hall is always lower than the living room and it can heat up too much. I want to put Thermostat in living room and have receiver in position of old Thermostat
     
    Last edited: 12 Sep 2021
  8. flameport

    flameport

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    The old thermostat switches 230V.
    It is not powered by 230V, as it doesn't have a neutral connection, and most obviously it also has 2 AA batteries inside.

    If you connect the unused black to neutral wherever the other end is, and install the receiver where the old thermostat was, and use the brown for L and the black for N and the grey for switched L, the receiver will have power when the programmer is set for heating on.

    When the programmer is off the receiver will have no power. The battery thermostat will then waste the batteries away trying to contact the unpowered receiver.
    End result - new batteries required every month.

    Given it's a Salus, it will probably unpair itself at regular intervals as well, perhaps every time the programmer switches the heating off.
     
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  10. Zooropa68

    Zooropa68

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    I was hoping this would be straightforward, but maybe not.

    I guess I could power the receiver via a separate external mains cable live and neutral, and just use same 2 wires which are for original thermostat.
     
  11. flameport

    flameport

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    Only if that external cable is connected to the same 3A FCU that supplies the rest of the heating controls.
     
  12. Zooropa68

    Zooropa68

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    Is that the regulations?
     
  13. EFLImpudence

    EFLImpudence

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    I am sorry I did not realise the limitations of the device. I assumed the thermostat was a timer as well.

    All you have to do is install the receiver near the programmer, wiring centre or boiler; wherever the appropriate wiring is.
     
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  14. Zooropa68

    Zooropa68

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  15. Taylortwocities

    Taylortwocities

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    Yes it is.

    consider a plumber, perhaps, working on the heating system. He/she would expect that turning off the boiler at its isolation switch would disconnect power from the whole of the system.
     
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