Replacing analogue thermostat with digital (1)

Discussion in 'Plumbing and Central Heating' started by Cgallen, 5 Nov 2021.

  1. Cgallen

    Cgallen

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    Hi I have 3 zones in my house with analogue thermostats, I want to upgrade to the Honeywell home dt90 can anyone point me in the right direction for the wiring I’ve attached pic of the analogue wiring and the back of the new thermostat casing any help much appreciated
     

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  3. Cgallen

    Cgallen

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    This is the analogue thermostat wiring diagram
     

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  4. sxturbo

    sxturbo

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    .
     
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  5. Cgallen

    Cgallen

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    Black or grey? Thanks
     
  6. CBW

    CBW

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    Live and switched is easy enough (1 and 3 to A and B respectively), just unsure about the other one, either pump or motorised valve?
     
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  7. Cgallen

    Cgallen

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    3 to a and 1 to b?
     
  8. Cgallen

    Cgallen

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    And it’s a motorised valve
     
  9. CBW

    CBW

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    No, 1 to A and 3 to B.
    Not sure how this would work with the DT90, sorry :notworthy:
     
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  11. sxturbo

    sxturbo

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    Is say grey to c.

    But it's not that clear
     
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  12. CBW

    CBW

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    No, C is off position (normally closed)
     
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  13. EFLImpudence

    EFLImpudence

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    Your present thermostat is actually wired the wrong way round - assuming brown is Live.

    It should be Live to 1 and Switched Live to 3 - which will be L to A and SL to B.
    That's all you should need.

    upload_2021-11-5_18-51-33.png

    Where is the lamp shown in the diagram
     
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  14. Cgallen

    Cgallen

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    Tried this with and without grey in c not working do I need to bridge anything like the analogue one was ?
     
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  15. Cgallen

    Cgallen

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    hi the old stat was working can’t get this thing to go at all ‍♂️
     
  16. EFLImpudence

    EFLImpudence

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  17. EFLImpudence

    EFLImpudence

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    All you should need is L(brown) to A and SL(black) to B.

    Just put brown and black together in a connector block and see if it works.
     
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