Wiring a room thermostat -central heating

[needhelpplease]

I've just bought a Honeywell programmable room thermostat (CM900) to replace an old Honeywell mechanical room stat. I need some advise on wiring the new one up.
If you are familiar with these then on the old stat there are 3 wires. There is a red wire to terminal 1. Black to terminal 2 and an unsheaved wire to terminal 3.
The new stat wiring diagram shows only 2 cables: live to terminal A and another wire to terminal B from the zone valve (Honeywell powerhead V4073).
So presumably I should put the red wire into terminal A.
What do I put in terminal B??
Any suggestions please.
Cheers
PS If you want the wiring diagrams let me know and I will try to upload them

 

[gas4you]

Firstly your original stat appears to have been illegally and dangerously fitted

The bare wire you have should be for the earth only

You must not use that for any live or neutral connection.

Others on here will point you to the Honeywell wiring configuration.

 

[plumberman_uk]

if u have now a 2 wire roomstat you can wire it up omitting the earth wire,, though a bit of knowledge on your side would be helpful... i am guessing you have 2 two port valves?
find the wiring centre and open it,AFTER YOU TURNED THE BOILER ELECTRICS OFF!!! here is what u need to do,,,

the red wire is already coming from no 4 on the programer ( heating on) so u can leave it as it is,, connect the red wire from the old room stat to terminal A and the black wire to B now fint the black wire from the roomstat inside the wiring box (wich is somewhere together with all the neutrals) and connect it to the brown lead of the heating 2port valve,,, take the wire out thats already in there wich should be your eartwire and just in case.. make it safe with a terminal block. thats it.. good luck and dont electricute yourself lol!