Installing CM927 on valliant ECOMAX

[sparkos]

Hi.
Firstly, thank you if a response is given to my query.

I have seen a few post regarding installing Honeywell 927 thermostats but wanted to clarify my setup to see if clear advise could be provided.

Currently I have an analogue Honeywell connected into a Vaillant ecomax boiler via bins 3, 4 and 5. I want to replace this with a Honeywell CM927 and wanted to see if it is possible without running new cables.

Could someone please advise how to connect a CM927 to a vaillant boiler and if I need a 4 core or will a 3 core be sufficient.


Thanks again

 

[Dan Robinson]

927 or 907?

 

[Charnwood]

Just to clarify Dan's question:
927 - remote RF sensor/controls with receiver wired to boiler
907 - sensor/controls direct wired to boiler

 

[sparkos]

I'm all for the universe making me a better idiot.

In this instance though its the CM927 as listed in my original post, I'm not sure what type of ECO Max boiler it is.

 

[sparkos]

Hi, would anybody be able to offer some assistance.

I understand that on the vaillant pin outs 3, 4 and 5 are the area to connect, but I am unsure how to connect the 927 to these connects

 

[Dan Robinson]

Honeywell L & N to Vaillant L & 5

A to 3, B to 4.


Or

Honeywell L & N to Vaillant L & N

A to 3, B to 4.

 

[sparkos]

So it definitely needs 4 connections I can't use a 3 pair and connect the second L to the A

 

[Dan Robinson]

Only if you put the Honeywell L to Vaillant 3.

And by Honeywell L, I mean the one on the left.

Then link the Right side L to A.

 

[Dan Robinson]

But you shouldn't be using the earth core as a conductor.

 

[sparkos]

So would that be
Vaillant - 927
L - L
L - 3
4 - B
5 - N

 

[Dan Robinson]

No.

 

[Dan Robinson]

Honeywell Left L - Vaillant 3
Honeywell N - Vaillant 5
Honeywell Right L - Honeywell A
Honeywell B - Vaillant 4

 

[Dan Robinson]

Do not use Earth as a conductor.


This is all in the manual(s) by the way.

 

[Agile]

Will any of the more sophisticated Vaillant controls modulate an Ecomax?

 

[Dan Robinson]

No mention of eBUS in the book.