New 7D programmer wiring advice

[Plums]

Hi All,

I'm looking at replacing my central heating programmer, currently an early version of the Drayton Lifestyle LP522 (installed around 2000). I want to get a 7 day programmer with boost options etc, that I don't currently have. I was looking at either the Drayton LP722 or the Honeywell ST9400C.

The water and heating are controlled seperately with the current system, and I'd want to keep it that way.

Basically, I'm unsure of the wiring and whether the existing wiring to the backplate would work if I just replaced the programmer? I've tried to look at some of the wiring diagrams available on Drayton and Honeywells site and thought it looked straight forward enough, until I took the programmer off and noticed that the wiring doesn't look as it should do now according to the current diagrams. (Maybe the wiring has changed on these programmers over the years?).



I thought from left to right it should go: N, L, HW OFF, CH OFF, HW ON, CH ON.
But as you see from my photos, there is nothing attached to HW OFF or CH OFF. Maybe they've just shorted these to the N terminal?

If anyones able to help advise that'd be great.

Thanks

 

[Howsie]

You generally don't have wires to those so wire up accordingly and you should be fine

Of course, take all the usually precautions when working with electricity.

Good luck.

 

[stevetheplumber]

you willfind the back plate is standard to many programmers from that wiring i would think you have a s plan with 2 seperate motorised valves as y plan use one of the off terminals

 

[Plums]

Thanks for the advice guys. Sounds like I should just get one and give it a whirl (safely!).