Wireless CMT 927 with 9400C timer: Y Plan wiring

[MickOC]

Hi,

I have ordered a CMT927 but want to make sure I'm 100% correct with wiring for my Y plan system.

I intend to use the existing 9400C timer for HW only, so I remove CH ON on term 4 at either end

I wire L(1) and N(2) up to Receiver, connect A to terminal 4 and B to terminal 5 (white to mid pos valve).

Do I also need to put a link between CMT927 receiver A (on 4) and Live (on 1)?

Thanks

 

[matt1e]

Hi,

I have ordered a CMT927 but want to make sure I'm 100% correct with wiring for my Y plan system.

I intend to use the existing 9400C timer for HW only, so I remove CH ON on term 4 at either end

I wire L(1) and N(2) up to Receiver, connect A to terminal 4 and B to terminal 5 (white to mid pos valve).

Do I also need to put a link between CMT927 receiver A (on 4) and Live (on 1)?

Thanks

Hi mick
link A to live and take B directly to 5 (valve white)
you dont need the A to 4 connection

so to recap

wire L(1) and N(2) up to Receiver, link A to live connect B to terminal 5 (white to mid pos valve).
this way you can use one cable, 3 core+earth

Matt

 

[MickOC]

Great thanks Matt, so I have 2 x Live connections into receiver?

Receiver A to 1 and Receiver Live to 1?

 

[matt1e]

Great thanks Matt, so I have 2 x Live connections into receiver?

Receiver A to 1 and Receiver Live to 1?

well you will have 2 in as neutral is technically "live" too but I dont think you mean that so no

you will have one live in (from wiring centre 1 to receiver L)
then a link from receiver L to receiver A
then a switched live out from receiver B to wiring centre 5
(and of course a neutral from wiring centre 2 to receiver N)

out of interest do you have a standard room stat fitted now? as this will be an easy job if it is already wired with a 3 core+earth

Matt

 

[MickOC]

OK mate, gotcha!

No room stat fitted, so intention is to fit better programmer with room stat, kill 2 birds with one stone!

Thanks again.

 

[MickOC]

CMT927 arrived yesterday, installed receiver in airing cupboard and stat is located in hall, removed head off hall rad.

Existing programmer is used for HW control only and that works OK

This is the first time we have been able to have CH on without HW, I'm impressed with the stat, it works like a dream.

Took me a little while to understand that it doesn't have CH off timer as doesn't really need it!

Thanks again.



Next job for summer is to replace all TRV's as none are working properly (sticking).