Honeywell st699 to Hive 2

Discussion in 'Electricians' Talk' started by fooey, Nov 11, 2017.

  1. fooey

    fooey New Member


    I've seen a number of posts on here asking for the same advice but looks like the initial wiring was different hence asking again. I have a Honeywell controller that I want to replace with a Hive 2.

    Any help with mapping the wires to the new backplate would be much appreciated.

    Many thanks.

    Attached Files:

  2. MGW

    MGW Well-Known Member

    Before you start check the boiler is able to work with Hive. Some of the Bosch Worcester boilers have their own system and will not work with Hive, at least not correctly.

    There is two completely different ways for a thermostat to work with a modern boiler, one is simple on/off the other is to vary the flame height, the simple TRV also varies flame height so in real terms you don't want a thermostat which turns boiler on/off as it messes up the control.

    There is a universal system called OpenTherm which allows some mix and match, Nest uses OpenTherm and Nest will also link to TRV using IFTTT system, don't know if Hive will do the same but likely it will.

    So you have three items, the boiler, the thermostat, and the electronic thermostatic radiator valve head, in an ideal world they all need to talk to each other, other wise you get a high hysteresis i.e. a sine wave of temperature in the room with it varying up and down by in some cases 4 degrees. So you start with boiler as costs a lot to change them, and work out if the boiler has a buss system to allow a thermostat to adjust flame height, if not all is not lost, systems like EvoHome can be set so it monitors the eTRV and only when all valves report satisfied does it switch off, but the cheap and nasty systems like Hive and Nest do not do that, best they can do is use a follow command using IFTTT however Nest as said does have OpenTherm so will work reasonably with OpenTherm boilers but not with boilers without the Buss system.
  3. Bazza

    Bazza Well-Known Member

    I don't believe my eyes. Its a heating thermostat with the switched live conductors properly sleeved in red!

    That must have been installed by an electrician, and not a plumber! :D
    Deleted member 33931 likes this.
  4. fooey

    fooey New Member

    So not sure I set this up correctly but I got it working based on what was there -

    Removed the bridging wires and then Honeywell -> Hive

    1 -> Live
    2 -> Neutral
    3 -> 4
    6 -> 3
    8 -> Live (!)
  5. MGW

    MGW Well-Known Member

    From the hive page 10 we get.

    8 = Com hot water = not independent on hive so likely L permanent line.

    7 = NC hot water = 1 on hive.

    6 = NO hot water = 3 on hive but not used.

    5 = Com heating = not independent on hive so likely L permanent line.

    4 = NC heating = 2 on hive but not used.

    3 = NO heating = 4 on hive.

    N = Neutral = N on Hive

    L = Line = L on Hive.

    So it would seem it will work if your boiler does not need volt free contacts.

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