Honeywell ST699 to ST9400C

[Mattjazz]

Hi, I decided to replace my old ST699 programmer with a ST9400c. I followed the attached diagram but I have no CH off wire. The CH now runs constantly even on the timer. Any ideas Please?

 

[lloyda]

Photo of your new wiring might be useful.

 

[Mattjazz]

Sorry, here you go.

 

[CBW]

You don’t need a heating off, only hot water off, which is your incorrectly used green/yellow. It could be your 3 port valve has failed coincidentally. Are you able to wire the 699 back in to test?

 

[Mattjazz]

Thank you for response.
Unfortunately not. Is there another way to test?
Following the Honeywell replacement wiring diagram it shows the green/yellow wire from 7 to 1. Is there a reason why it should be in 2?

 

[stem]

Following the Honeywell replacement wiring diagram it shows the green/yellow wire from 7 to 1. Is there a reason why it should be in 2?

It shouldn't be in T2 as @CBW CH terminal 2 'CH Off' isn't used, it wasn't used on the ST699. Terminal 4 was vacant.

The connections also look correct to me:

Green / yellow wire used as HW Off [ST699-T7] =[ST9400c-T1]
Dark Grey wire used as HW On [ST699 -T6]=[ST9400c-T3]
Light Grey 2 wire used as CH On [ST699 -T3]=[ST9400c-T4]

Blue wire = N
Red wire = L

Has anything else changed? Did anything happen during the installation, such as a fuse blowing? Did it work correctly before the ST9400c was installed?

The CH now runs constantly even on the timer.

Is there a timer somewhere else, or do you mean the ST9400c programmer?

If you were to remove the Light Grey wire from ST9400c terminal 4, isolate it and replace the programmer, does the central heating still run? If the answer is no, there is a fault with the ST9400c, if its yes the fault is elsewhere.

 

[Mattjazz]

Ok, having taken off the faceplate to take a photo of the current wiring, it all seems to be working ok now.
Fingers crossed it stays that way, if not, I’ll be back!
Thank you for the help.

 

[Mattjazz]

Just another update, I REALLY SHOULD READ THE INSTRUCTIONS!
i hadn’t copied the on/off times to the different days so it was running on the factory presets.
Again, thanks for the help.