Honeywell CM927 & Potterton Performa 24 Combi

[tcanact]

Hi,

I'm looking at purchasing a thermostat for my Performa 24 and have come across the CM921 / CM927 controls by Honeywell which seem to get a good writeup.

From what I have read, this would be suited to the boiler however there is a section the the manual that states "NOTE: If the room thermostat being used incorporates an anticipator it MUST be wired as shown in Fig. 37."

This bit is confusing me slightly and I was wondering if anyone could point me in the correct direction?

Thanks

 

[Dan Robinson]

Ignore that - it is for old fashions room stats.

You wire terminals A and B across the boilers internal room stat connections, and feed the receiver form the boilers own live and neutral connections.

 

[namsag]

Equivalent of anticipator is already built into the 921/927.
Take the receiver live and neutral from the fused spur as the connections in boiler are not really big enough for 2 wires to go into .
If no existing room stat just remove link in boiler and connect A an B on reciever to it.

If you have an integral clock already fitted put this onto constant

 

[tcanact]

I have finally got around to purchasing a CMT927 and have today connected this up to the boiler with connections A & B in the relay receiver (BDR91) to connections 1 & 2 within the boiler with the link cable being replaced.

This works and the stat turns the boiler on and off as required, although I have found that when the relay is disabled (green light is off) due to the stat being up to temperature the DHW doesn't work.

Any thoughts on what I have missed or have done wrong?

Thanks

 

[Dan Robinson]

More likely you have broken something.

 

[tcanact]

More likely you have broken something.

Thanks for your reply, although apart from stating the obvious it wasn't much use!

Anyway, I think I have sorted the problem. After taking the boiler covers off the DHW started working working. I can only think that a stray cable was obstructing the microswitch hence no hot water.

 

[Dan Robinson]