Mechanical thermostat to digital

Discussion in 'Plumbers' Talk' started by rizla13, Dec 26, 2018.

  1. rizla13

    rizla13 New Member

    Hi

    I have a british gas branded thermostat RTS4
    I want to change it over to honeywell dt90e

    Just a little confused with existing wiring and where it would go into the dt90

    Currently wired as
    Grey into N
    Brown into L
    Black into 3
    Earth into L and 1
     

    Attached Files:

  2. Mike83

    Mike83 Screwfix Select

    Is the dt90 battery powered.
    Do you have a pic of the wiring for the new stat
     
  3. Mike83

    Mike83 Screwfix Select

    Ignoring the earth (link) you have 3 wires:
    Live
    Neutral
    Switched live
     
  4. rizla13

    rizla13 New Member

    So the black wire is going into the call connector on the rts4. This is the switch live wire?
     
  5. rizla13

    rizla13 New Member

    I haven’t purchased it yet but it will be the battery operated one. I got a screenshot of the manual
     

    Attached Files:

  6. Mike83

    Mike83 Screwfix Select

    So would only require the brown and black.
     
  7. rizla13

    rizla13 New Member

    Ok. So which colour would go into the dt90 as it labelled abc?

    And just out of your advice what is the best digital thermostat to go for or is this good?
     
  8. Mike83

    Mike83 Screwfix Select

    Brown A
    Black B.

    There’s that many stats on the market.

    What are you looking to gain by replacing the stat. Can maybe advise a bit better with more info.
     
  9. rizla13

    rizla13 New Member

    Accurate temperature
    The current one i got has got play in it. It quite a few degrees out. Eg if i set it to 20 it probably really is 25 before heating fires up. I hope I explained it correctly
     
  10. rizla13

    rizla13 New Member

    Also just out of curiosity why is grey neutral not getting used?
     
  11. Mike83

    Mike83 Screwfix Select

    Some stats require a neutral and done don’t.
     
  12. Mike83

    Mike83 Screwfix Select

    Most stats work the same way. If it’s set to 22 if won’t always go on and off at 22.
    If it did this it would be constantly be going on and off. So there’s a bit play either side of the setting so it’s not cycling on and off as frequently.
    If you want a stat with a digital reading then the one your thinking about is fine.
     
  13. rizla13

    rizla13 New Member

    Ok thanks for your help
    Lastly is there a version of the dt90 stat i can get without battery? So the display works from mains?
     
  14. Mike83

    Mike83 Screwfix Select

    You don’t have a mains.
    You have a Live into the stat from the programmer.
    A live out from the stat to the boiler.
    And a Neutral.
     
    retiredsparks likes this.
  15. rizla13

    rizla13 New Member

    Ok. So dt90 is the only option

    Thanks for your help. Much appreciated
     
  16. rizla13

    rizla13 New Member

    Do i just wrap insulation tape around grey wire once I install the dt90 and tuck it away?
     
  17. Mike83

    Mike83 Screwfix Select

    Use a terminal strip then cover in suitable tape.
    There’s lots of battery powered stats on the market that will let you have the digital display.
    There’s also lots of dial type stats that are suitable for your current wiring.
     
  18. rizla13

    rizla13 New Member

    Do i need to get a certain amp rating terminal strip?
     
  19. Mike83

    Mike83 Screwfix Select

    3 will be fine
     
  20. rizla13

    rizla13 New Member

    Thanks for all your help. Once i have got the dt90 and fitted I’ll update on here
     

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