Honeywell T6360 Thermostat

Hi I have changed my Honeywell T6360 thermostat to a Salus T105RF wireless thermostat.
There was three wires going to the original honeywell thermostat. One of these being the supply and another going to the boiler. I wasn't sure what the other wire was and so didn't connect up.
Now the Salus thermostat has been working fine, but when the thermostat is not calling for heat and there is demand for hot water (unvented hot water cylinder) the radiators are still getting warm.
Am I right in thinking that the other wire is for the heating 2 port valve?
If so, what terminal do I connect the valve wire too in the Salus reciever unit as there are only two terminals (NO & COM)?
Do I just connect the valve wire to the same terminal as the wire to the boiler?
Thanks for any advice/help
David

Sunvic port valve ?

No, honeywell 2 port valve.

Why does it have a wire in port 4 then eg heating off ?

I have three 2port valves, two for both hot water cylinders and one for the heating.
I'm assuming when the programer is calling for hot water and the heating thermostat is not calling for heat the valve is not closing. I think maybe the wire is for this valve hence it not closing under the above conditions?

Sounds more like the heating zone valve isn’t shutting off. How come you have x2 cylinders?