Wiring cm927 to a combi ultracom cxi (glow worm)

[foster25]

Hello

Has anyone got any experience wiring a honeywell cm927 to an ultracom combi boiler?

I am working with a registered boiler installer but we are both unsure as to how this should be wired, we have tried a few options but to no avail

would appreciate any help anyone might be able to give

thankyou

 

[foster25]

please see wiring diagrams bellow

Untitled

• foster25
• 11 Feb 2013
• 1

Untitled

• foster25
• 11 Feb 2013
• 1

 

[D_Hailsham]

Connect BDR91 L and N to L and N in the boiler.

Remove link between 24v and 0 terminals
Connect A to the 24V terminal and B to 0

Do NOT link L to A

Untitled

• D_Hailsham
• 11 Feb 2013
• 1

 

[foster25]

Many thanks D_Hailsham for your reply and very clear explanation, its much appreciated

But i am a little confused as i also contacted honeywell technical support with the same question and the response i got was as follows

N = Neutral
L = Live
A = OTC1
B = OTC2

is this incorrect then?

 

[D_Hailsham]

But i am a little confused as i also contacted honeywell technical support with the same question and the response i got was as follows

N = Neutral
L = Live
A = OTC1
B = OTC2

is this incorrect then?

Yes; it's incorrect.

If you look at the Key in the top left corner of your first pic you will see that it says: OTC - Outdoor sensor connection. They are for use with a weather compensation system, which you don't have, that uses an external temperature sensor to control the temperature of the boiler.

Follow my wiring.

 

[foster25]

Hey D_Hailsham

I just wanted to say thankyou for your help, we followed your wiring and its all set up and working nicely

Could i just ask if you would reccomend fitting an outdoor sensor to the boiler also?