Need Help Replacing old Honeywell Dial Thermostat With new Honetwell DT90E Help and information on all topics relating to your central heating, air conditioning and ventilation issues.

[reddwarfcrew]

Hi, I'm replacing an old honeywell dial thermostat (T6360B) with the DT90E.

The old one surprisingly has 4 wires:

Yellow/Green to earth
Brown to T1
Grey to T2
Black to T3

The DT90E has A/B/C terminals. Can someone help with which 3 wires go where and which is redundant.

Thanks for any help.

Pics attached.

[proptech]

Hi
Your new stat does not need a neutral or an earth. So make the grey and the green/yellow safe within the housing. Connect the brown to A, and the black to B.