Replacing Vintage Honeywell thermostat with TADO V3+ smart wired Thermostat

Gerrya

Hi all, looking for some help as per above Replacing this old Honeywell Thermostat (no model number may have been on the outside but covered in paint.

Wiring looks like this:

This translates to Yellow in 2, Blue in 3, Red in 1. with an earth hidden in the back.

I have put up the TADO and wired as follows:

Yellow in NO, Blue in P1, Red in COM, Earth in P2 this is connected to a British Gas 330+ Condensing Boiler. Everything comes on but on the TADO it does not put the CH on. I have also read some Relay ON/OFF and checking through this the boiler comes up under D07 . Now that part may be a big red hearing am at a lost. I was planning the second part to replace the old timer ( Randall 702 manual but always worked.)

Within the Tado app I can actually see when I put the heating time section on.

wateroakley

Hello @Gerrya From the your picture and a the Tado wired room stat picture …

• Yellow 2 is NEUTRAl. Tado: Park 1.
• Red 1 should be LIVE ('Call for heat' from controller timer). Tado: COM.
• BIG CAVEAT for Blue 3 'Call for heat' or 'heat satisfied' from the thermostat?. It's not possible to be certain Blue 3 is Tado NC or NO. Typically, a room thermostat would be wired 'Call for heat on Tado NO. Looking at the diagram, this implies the old thermostat may be wired as 'heat satisfied' on 3 (like a frost stat) and would go on Tado NC. The only way to check if Blue 3 is Tado NO or NC is with a multimeter or voltage tester.

wateroakley

Hello @Gerrya Welcome. It's hard to say which model this is. Old manual thermostats typically had three wires: LIVE LOAD and NEUTRAL. You'll need to figure out which is LIVE (COM) from the controller, and LOAD (NO) to the zone valve or boiler. For Tado, Neutral should be parked safely.

The rear of the front panel often had the printed wiring diagram. Using a multimeter is often the best way to figure this out.

This diagram is from a vintage Honeywell T6360B.: LIVE (from programmer) =1 (COM). LOAD (to zone valve or boiler) = 3 (NO). NEUTRAL = 2. No wire = 4 (NC).

Gerrya

Thanks still not working my diagram of the old one is

With a Red cable in 1, Blue in 3, Yellow in 2. ?

Gerrya

Right folks all hail the multimeter. The changes you suggest are correct. Howvever the previous owner ignored the colours of the cables and did his own thing. So every change made at the Tado was wrong. Until the Time/Clock end was tested and re wired with the appropriate wires according to colour in the correct. So now fully working final pic to show. Thanks all

wateroakley

@Gerrya Pleased to hear that the multimeter has been elevated to Chief and your Tado is fully working.