Installation of Thermostat Issue - Help please

Discussion in 'Electricians' Talk' started by Matt260689, Mar 16, 2021.

  1. Matt260689

    Matt260689 New Member

    Hi guys/ girls

    I’m after some help with my current situation...

    I have purchased a smart thermostat to replace the old one on the wall.

    so my old thermostat is wired to the wall, I will attach a picture.

    wired by two cables one black one brown.

    there is a third (grey) which is not in use.


    I have wired the new thermostat and it comes on etc however when I go to change the temp higher so the actual heating comes on it then makes a slight sound then powers off and comes on and repeats... only does it when I change temp up higher to activate heating , it seems like it’s short circuit maybe? (Sorry not an electrician so not sure if that’s the right term for it...)

    links to photos (wouldn’t let me upload as says file too big)

    https://ibb.co/4fJt8xT
    https://ibb.co/RB1HXb3
    https://ibb.co/cNT02fT




    Any help would be greatly appreciated!
    Thanks in advance
     
  2. Philip Hyde

    Philip Hyde Screwfix Select

    So how have you wired it as You only have two wires. This stat needs Live Neutral and a switch return back to the boiler. Have you got pictures of how it was wired and how you have wired it. Your old stat is battery powered not mains.
     
  3. Matt260689

    Matt260689 New Member

    Hi Philip,

    Cheers for the reply

    so here is how the current stat is wired

    Picture: https://ibb.co/f9MnTJz

    And on the new stat I have basically replicated how it’s wired on the old

    so the brown to connection 4 and black to connection 5...

    From what you are saying, is it not going to work with just those two cables?

    I know a google nest works but this is a much cheaper version off Amazon ...
     
  4. Philip Hyde

    Philip Hyde Screwfix Select

    Right you might be able to make it work but will entail a bit of work. What Boiler is it you have. Make and model number.
     
  5. MGW

    MGW Screwfix Select

    As far as I am aware the only Smart thermostat that will work without a neutral is the Nest e. I know of no others.
     
  6. Philip Hyde

    Philip Hyde Screwfix Select

    But He has a spare grey wire so might be able to put a neutral in. Just depends if boiler needs switched live or clean switch contacts
     
  7. MGW

    MGW Screwfix Select

    Yes even if not a spare wire he can run a new cable, and not even down to just boiler, it may be the thermostat controls a motorised valve which in turn controls the boiler, or the boiler may use MODBUS, there are all sorts which can be done.

    But a like for like change from a battery powered thermostat to a thermostat which also has "Smart" functions, which is also battery powered the only option as far as I know is Nest e.

    I don't like Nest, I have Nest Gen 3, which I bought because it should have worked with my Energenie MiHome TRV heads, but support it seems has been withdrawn, reading the spec it seems likely the Drayton Wiser is the best at moment as it uses algorithms to speed up the room warming in the TRV heads. EPH also can work with multi-zones, and there is always the Honeywell EvoHome which was one of the first "Smart" systems, but that is not what is being talked about. We are shown a battery powered thermostat which the guy wants to swap for a smart thermostat, and however much I don't like Nest, in this case the Nest e is the easy way to add smart functions.
     

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice