N
Nindy
Hi could someone pls advise me ?
I currently have a t40 Honeywell rotary stat and want to replace it with DT90e stat.
The dt90e has A= live B= Switched live C= ? Correct if I am wrong pls.
Old stat has blue wire connected to 1, brown wire connected to 3 and earthed BUT I think the colour of the wires do no resemble live and neutral if that makes sense. When I put a voltage screwdriver to blue and brown they are live when the heating is on. When the stat is off only the brown lights up.
On the Main 24he boiler it says connect switched live to term 2 and perm live to 230 volt term one i think is this correct.
So only a live and switched live is required for the DT90e stat, it uses batteries to run the stat as well.
Could some pls confirm how to wire this up as I don't want to mess it up !
I think its the following :
From old stat term 1 has brown wire ( which is constant live) which goes to DT90e term A
From old stat term 3 blue wire ( which I think is switched live) goes to DT90e term B
Blank off earth wire and thats it ?
Here's the diagram of the main boiler pls see below :
P.s Great forum !

I currently have a t40 Honeywell rotary stat and want to replace it with DT90e stat.
The dt90e has A= live B= Switched live C= ? Correct if I am wrong pls.
Old stat has blue wire connected to 1, brown wire connected to 3 and earthed BUT I think the colour of the wires do no resemble live and neutral if that makes sense. When I put a voltage screwdriver to blue and brown they are live when the heating is on. When the stat is off only the brown lights up.
On the Main 24he boiler it says connect switched live to term 2 and perm live to 230 volt term one i think is this correct.
So only a live and switched live is required for the DT90e stat, it uses batteries to run the stat as well.
Could some pls confirm how to wire this up as I don't want to mess it up !
I think its the following :
From old stat term 1 has brown wire ( which is constant live) which goes to DT90e term A
From old stat term 3 blue wire ( which I think is switched live) goes to DT90e term B
Blank off earth wire and thats it ?
Here's the diagram of the main boiler pls see below :
P.s Great forum !
