That's what I thought; but you can't be too careful, particularly when advising remotely.
Right, here goes (some of this is tidying up, i.e using correct colours where possible):
Turn the power off
At Programmer
Disconnect Brown, Blue and G/Y fromT1, T2 and T3
Connect Blue to T1 and Brown to T2. (Green/Yellow is not required so it should be made safe - insulating tape or terminal block.)
At Terminal Block
Disconnect Brown from T1, G/Y from T2 and Blue from T3 (cable from programmer)
Connect Blue to T1 and Brown to T2. Green/Yellow is not required so it should be made safe - insulating tape or terminal block)
At T603a Thermostat
Disconnect all wires
Make the G/Y safe
Install the new DT90E Thermostat
Connect Brown to A
Connect Blue to B with some red sleeve or insulating tape round it to show it is switched live
At terminal block
Disconnect the cable from the thermostat (T2=G/Y, T3=Blue, T10=Brown)
Reconnect Brown to T2
Reconnect Blue to T10 with red sleeve/insulating tape
Make the G/Y safe
Turn Power ON
Job Done
D_Hailsham; Thats fantastic;your a star.
I'm off to the local merchants in the morning to get the DT90e. I was waiting for confirmation of its suitability given my wiring arrangement. Will post on progress.
Once again many thanks and regards,
Benny.
