Programmer NC HW wire - is it a trap?

[edteamslr]

Hi - dramatic title but I'm fitting an Evohome HW and HTG smart thermostat/TRV/relay system.

When I traced all the wires to the programmer and beyond I found that the HW normally-closed pin in the programmer had a wire attached to it. It was linked to permanent Live and had a red sleeve on it (old wiring). I can tell because it is also linked via the control centre back to Live on programmer and live on the zone valves. Is this right and why?? Any theories?

I have a Maxiflo with Baxi boiler in S-Plan with 2x zone valves.

 

[Echo the husky]

What programmer do you have? If it is wired as you say it would serve no purpose, as the switched power would go nowhere when off. Pictures please.

 

[DP]

May have been a Y plan at one time

 

[edteamslr]

The earth at 7. Control centre (not particularly neat)

 

[edteamslr]

Funny how I just saw this in the PDF:

(Mine is definitely an S-plan with two zone valves, each with one pipe in and one out)

 

[DP]

Honeywell Sundial wiring plan is almost universal
Following that pattern left to right would be, supply live, neutral and then earth, ch from timer, ch from room thermostat, HW from timer, HW from cylinder thermostat etc

Your wiring seems to follow that pattern apart from first three.
Also use of earth as current carrying conductors is bad practice

 

[edteamslr]

Thanks @DP. The EVOhome system uses two separate BRD relays (HW/HTG) so it feels like I can include or remove that cable on 7(NC) in the HW BRD without affecting anything.