How can I find the installation guide for replacing a Drayton Digistat 3 with a Tado Smart Thermo?

Tony212

I’d like to replace the old Drayton Digistat 3 thermostat in a self-contained flat with a smart thermometer, and before buying the new one want to check the wiring to make sure it’s an easy swap.

It runs off the same boiler as the main house, operating as its own zone, and has three wires feeding it.

I thought the Tado App would give me a guide, but it seems to want to scan the new unit before it’ll let me access the guide to the wiring.

policywonk

Question: is this digitstat only handling central heating, or does it also control a hot water tank in your apartment?

Need some information. Please provide us with a photo of the back wiring of the Drayton, and use a mains testing screwdriver to tell us which pins light up the screwdriver.

This picture:

comes from the installation guide for your Digitstat 3. According to this it has:

• ONE LIVE INPUT
• ONE NEUTRAL INPUT
• ONE EARTH STRAP.
• With these poles activating a motorised valve:
  • BL(ue)
  • BR (own)
  • GR(ey)
  • O(range)

You will need a Tado Wired thermostat. Provide this information to Tado support by email and ask them for instructions to install. If confused by their answer, come back here and we'll help.

Tony212

It controls only one zone of the central heating, a zone that is always “live” such that at any time, 24/7, if the thermostat calls for heat the boiler comes on, and hot water is pumped through the radiators for that zone.

I’ll add the other information when I can post from my computer; I can’t work out how to attach a picture from my phone.

Edited to add…

The back plate has three wires, labelled (unhelpfully) 1,2 & 3, coloured (respectively) white brown and black.

policywonk

No posts can be submitted from a phone. A computer - yes that works.

How do those wires map to the drawing I gave you earlier? Dont forget to test the pins with a mains tester.

wateroakley

@Tony212 Hello. The V3+ wired starter kit should be a straighforward replacement for the Digistat +3 programmable thermostat.

For an Annex, the issue to check is how far away the Internet Dongle, that connects Tado via your ethernet/broadband, will be mounted from the wired thermostat?

Tony212

Here's the back plate. The central wire's live, the other two are not.

policywonk

Hello again. Isnt this just fun? It turns out there are two Digitstat 3 models, which have the same model, with the same front, but a different back! For your version this is the wiring table:

According to that table, the wires map to a Tado thermostat as follows

PIN 1 goes to COM

PIN 2 goes to CH NO

PIN 3 goes to CH NC

The Tado thermostat should be set to Relay mode (R01).

Am a little worried that only PIN 3 showed up as live. Please double check. If it comes back as the only one that is live again, there is a possibility that your thermostat was wired with PINs 1 and 3 swapped. If this wiring map given above doesnt work, I would recommend you change the wiring to the following version:

PIN 1 Goes to CH NO

PIN 2 Goes to COM

PIN 3 goes to CH NC.

If that results in nothing working, please put back the Drayton wiring to the way it originally was, replace the Digistat and ask whoever provided that apartment to verify the wiring.