Boiler thermostat instalation

Discussion in 'Electricians' Talk' started by Jessica Roscoe, Dec 29, 2022.

  1. Jessica Roscoe

    Jessica Roscoe New Member

    My partner bought a BOT 313Wifi thermostat for our volkera boiler (Installed 2016) assuming I'd have no trouble wiring it up!

    Trouble is, I'm not certain and don't want to cause any short circuiting! Our existing thermostat is bluetooth via the wire below.

    Can anyone advise on which wire goes where??!
    My boiler wire, thermostat and the diagram are attached.

    Thank you!!!!
  2. MGW

    MGW Screwfix Select

    Boiler manuals normally say where to connect.

    Something like this upload_2022-12-30_0-5-45.png
    Since don't know your model can't look it up for you, there are basic four ways that thermostats connect to boilers, direct on/off extra low voltage (normally 24 volt) which needs volt free contacts, direct on/off low voltage (230 volt AC), indirect on/off low voltage vie the motorised valve, and varying voltage (normally 0 - 40) which alters the output of boiler, rather than simple on/off, there is a thermostat EPH which can both open and close the motorised valve and connect to boilers ebus with OpenTherm.

    However design of home, system, and boiler changes what is required, there is no one size fits all.

    Oil boilers normally simply switch on/off, gas boilers normally modulate (turn down) the latter is basic controlled by the thermostatic radiator valve (TRV) and the by-pass valve, and as the water returns hotter and hotter the boiler turns down more and more until it can't go any lower, then starts to switch on/off (called mark/space ratio) but this will not turn the boiler fully off, so a wall thermostat is used to turn off boiler on warm days.

    However we use near enough engineering, cost too much to have a fully controlled system, so when my wife's and my phones are detected as not being at home, my wall thermostat turns to Eco mode, i.e. warm enough to stop freezing, and to be able to re-heat in a reasonable amount of time, really should have each electronic head on each TRV set for geofencing, and they can with IFTTT, but just too much messing around, if boiler is not running, does not matter what the TRV does.

    The main thing is to work out what the boiler needs, putting 230 volt on a 24 volt or 0 - 40 volt terminals will wreck the boiler.

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