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Need Help Replacing old Honeywell Dial Thermostat With new Honetwell DT90E

Postby reddwarfcrew » Sat Mar 28, 2015 11:29 am

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.
New Thermostat.jpg
New Thermostat diagram
Old Thermostat 2.jpg
Old Thermostat diagram
Old Thermostat 1.jpg
Old Thermostat wiring
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Simply Build It

Postby proptech » Sat Mar 28, 2015 7:47 pm

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.
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