Wiring a Honeywell DT90 in place of a Potterton PRT100

[ookster]

Hello folks
Have a hopefully quick question.

Am taking off an old Potterton PRT100, has 3 wires connected.

No 3 terminal is black
No 2 terminal is red
No 1 terminal is sort of red (it's old and hard to tell)

The sticker on inside of cover (which states PRT100ST, though the outside emboss just states PRT100) describes:
3 as N
2 as H
1 as TL

On the Honeywell DT90 (not bought it yet) the manual has a variety of wiring options, there is A & B.

http://www.free-instruction-manuals.com/pdf/pa_457920.pdf

I have found another post on this forum discussing the same thing but their model of PRT100 is different from mine! So am a bit unsure.

https://www.diynot.com/diy/threads/hi-please-help-potterton-prt100-died.452417/

Can anyone please point me in right direction? Looks like I will have an extra wire to deal with.

Replies much appreciated.

 

[ianmcd]

1&2 on the old one to A&B on the new one and safely isolate the wire in 3 on the old one , that is a Neutral and no longer required on the DT90, it is battery powered

 

[ookster]

Very kind, thank you .