Wiring help - replacing salus rt500rf with honeywell cm927

4 Jan 2011
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United Kingdom

I have a Potterton Suprima boiler and a Center CH/HW programmer.

I previously had a wired thermostat. This was replaced a few months ago (not by me) with a salus rt500rf.

This has now failed (when the thermostat unit calls for heat, the receiver green light flashes on and then off several times before staying off).

Given the number of poor reviews, I'm looking at replacing it with a honeywell cm927. From an earlier post, i understand that this can just be wired in in place of the salus, and then if i leave the CH programme running continuously, the cm927 will control the heating full time.

Not being very familiar with how the boiler systems and controllers are wired up, I'm using the current wiring from the Salus as a guide (assuming the guy who wired it up was competent?!!).

The wiring diagram on the back of the current salus unit says there should be a link wire between the 'L in' (black) and 'L' (brown) if it was a 230v configuration. Given that there is no such link wire, I am assuming therefore that my system is a VF configuration? Not sure quite what this means, but the wires are currently set up as follows:

- black into 'Com'
- grey into 'NO'
- blue into N
- brown into L
- an empty port 'NC'

does this sound right? If not, is there a chance that the problem with the existing unit is actually the wiring rather than the unit itself? We haven't used the heating since the salus was installed so there is a chance it's never really worked!

Assuming then that the wiring is indeed sound, should it be quite easy for me to hook up the new honeywell cm927?!

Thanks in advance...

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