can I replace a Drayton Digistat 1 with a Drayton Wiser Thermostat?

Discussion in 'Plumbing and Central Heating' started by Grim1201, 30 Nov 2021.

  1. Grim1201

    Grim1201

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    Hi I am looking to upgrade our Drayton Digistat 1 thermostat with the Drayton Wiser Thermostat 1 kit but want to check wiring for the Heat Hub if anyone can help.

    So existing digistat is battery powered and has three wires for three connection prongs as follows.-
    Red into terminal 1 - which I believe is the common C
    Blue into terminal 2 - which I believe is the heating off (heating satisfied)
    Yellow into terminal 3 - which I believe is the heating on (call for heat)

    I have no fused spur to the thermostat.

    The backing plate on the current digistat is a little larger than the new one for the Heat hub so I will need to rewire. Am I safe to wire the new plate back in the same config as above mindful that the new plate has 6 positions?:-
    N
    L
    1 - Com
    2 - Off
    3 - On
    4 - ON although should be redundant in my case I only have a 1 channel hub.

    I can find plenty of info on how to upgrade a two wire battery thermostat and a 4 wire powered thermostat, but not a three wire existing battery thermostat.

    Advise please
     
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  3. ianmcd

    ianmcd

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    very unlikely that you will use terminal 2 heating off, what boiler do you have
     
  4. oldbutnotdead

    oldbutnotdead

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    The Wiser hub requires mains power so you'll need to organise that first (may be easier to locate the hub at the wiring centre).
    Also some (not sure if it's all) Wiser hubs don't have volt free contacts, if your boiler control is something other than 240v AC you could be in bother.
     
  5. stem

    stem

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    According to the OP's it is volt free, it has an external Common....
    ....sounds like this one:

    upload_2021-12-1_11-49-33.png
    As your existing Drayton Digistat is only a basic thermostat, that suggests that there will be some time control or programmer somewhere else. If so, it would be normal to remove the existing programmer (provided it's not an integral part of the boiler) and mount the Wiser there. The old thermostat wiring is then decommissioned which includes a small wiring mod.

    The programmer will already have a mains 230V supply to power it, but the Digistat 1 is battery operated, so there may not be a 230V supply present, and if not you will need to install one.

    At the moment we don't have a full picture. No mention of any stored hot water control so assume you have a combi boiler. If you have a hot water cylinder connected to the boiler, that changes things, and as per @ianmcd we need the info on the blue wire in terminal 2.
     
    Last edited: 1 Dec 2021
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  6. Grim1201

    Grim1201

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    it is a Ferroli F24 Combi Boiler. There is no current time controller for the heating hence why the desire to update with a smart controller which we can programme.
     
  7. stem

    stem

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    OK Thanks, but that's very unusual. Drayton Digistat 1 doesn't incorporate any time control, so are usually wired via a programmer or timeswitch.

    Capture.JPG

    If you are going to swap the Digistat 1 with the Wiser, you will need a 230V supply for the Wiser. Which should come via the same fused connection unit as the boiler.
     
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