Honeywell CM67 wiring problem - Brrrrrrrr

[nikosof]

Hi all
I replaced -rather tried- a vintage honeywell stat with a new cm67. the property has a potterton suprima L for heating (water is supllied through a separate(!!) water cylinder). The boiler is connected to a programmer, an Invesys/Drayton Lifestyle LP111.
The problems started when i tried to wire the cm67. it has 3 connectors, but there were 4 cables coming out of the wall. Red, Blue, Earth & a yellow one. I presumed that the red was live -into connector A- & the blue neutral - into connector B. I taped the yellow, but when trying to operate the system, the programmer fuse blew.

Please any suggestions re wiring would be greatly appreciated!!!

also, is there any use for the drayton or can cm67 operate by itself?

 

[ChrisR]

NOt surprised the fuse blew!
Probably the wires you need are the red and the yellow. The old stat would have needed a neutral, probably blue - so when your stat connected live, to neutral - pop. You should check the wires at the programmer etc really, but if all that can happen is blowing a fuse.....

 

[nikosof]

thanks Chris
so you suggest that i connect red to A and yellow -not blue- to B. in which case i tape blue and do not connect?
i have 4 spares

tks for the help!

 

[ChrisR]

Yup. Hope they're 3 amp fuses!

 

[nikosof]

oh, don't go there. thank god i've got a spare drayton 711.
never mix 13 & 3 amp!!! some things you learn the hard way.

 

[nikosof]

thanks Chris. It worked!