Changing Honeywell CM907 with a CM927 - reassurance please.

[JAD]

I am just about to change my CM907 with a CM927 wireless unit.
For various reasons, I want to place the receiver on the wall in my hallway where the CM907 is now situated.
I've got 3 wires running from my Worcester 35CDi Combi to the CM907, with only 2 in use for now. The 3rd wire is safely terminated at the moment and connects to Neutral (Ns) in the boiler.
My plan is to wire the unused wire from Ns in the boiler to N in the receiver. Ls(boiler) to A(receiver) and Lr(boiler) to B(receiver) and then link the 2nd L and A in the receiver with a brown sleeved wire.
I am sure this is correct and will work, however, I have just read in the installation guide of the CM927 that I should "Keep AC mains supply/load cables separate from signal wiring."
Should this worry me?
Any advice would be gratefully received.

 

[petertheplumber12]

Their advice makes sense but I have wired several and never kept the perm live separate always used 4 core and no problem yet, I think they are covering their backside that's all.

 

[doitall]

Take Ns to N as you say.

Ls to L.

Lr to B.

Link L to A.

for your information the 2 L in the reciever are not joined, if you use them both you need to add a link.

 

[Dan Robinson]

for your information the 2 L in the reciever are not joined, if you use them both you need to add a link.

Are you sure . *edit* yes you're right.... thinking of other things... long day.



For reference. The concern on keeping AC mains supply/load cables separate from signal wiring; is more todo with unduce voltage into LV control lines from adjacent mains voltage cores.

Not had this problem myself even with long runs of 5-core flex with LNE cores & 2 VF cores. But the possibility is there.

Thank the maker I can bring a relay into play should there ever be a problem

 

[mephisto]

for your information the 2 L in the reciever are not joined, if you use them both you need to add a link.

The diagram in the instructions shows the two L terminals as being connected internally, and they are.

 

[Dan Robinson]

That'll teach me to "double check" wiring diagrams after a second G&T

 

[Dan Robinson]

That'll teach me to "double check" wiring diagrams after a second G&T

 

[doitall]

for your information the 2 L in the reciever are not joined, if you use them both you need to add a link.

The diagram in the instructions shows the two L terminals as being connected internally, and they are.

They show a link between the 2 L in the MI's.

Just checked and there's continuity between E2 & E3 on the board so you are right.

 

[JAD]

Thank you everybody.
I've fitted the CM927 as suggested and it seems to be working very nicely, although I am a bit dubious about the accuracy of the current temperature showing? Perhaps I can recalibrate this if it turns out to be a couple of degrees out?
I had already wired it up with both the Ls wire and the link to A in the same L terminal on the receiver before getting confirmation that the two L terminals are in fact linked.......I'll leave it for the time being!

 

[doitall]

Thats how mine is wired so don't worry about it.

Is the stat in an influence that will affect the temperature,

 

[JAD]

No, but I have the old CM907 next to the new CM927 and they are giving different readings, which is what got me perplexed. However, I think they are settling down as the day progresses. Perhaps handling the new unit while programming it heated it up? Something that doesn't happen when programming the CM907, which stays screwed to the wall.

 

[Nagartath]

HI, I know this post is old, could you post a picture of the wiring into the receiver as I am looking to do exactly the same as you.

Thanks
Duncan