Boiler controls only working on auto

[Merrily]

hi,

My boiler will currently only trigger if the controls are on auto and the correct time is reached. If I try and press +1 or override, or turn it to continuous/once whilst it is off it will not trigger the boiler, although the light on the control panel comes on. This applies to hot water as well as central heating. Any ideas as to what the problem is likely to be?
Thanks

 

[D_Hailsham]

Which boiler do you have and which controls?

 

[Merrily]

It’s a Honeywell ST9400C 7 Day 2 Channel Programmer and a Main HE Boiler, I’m not sure of the model but it is not a combi boiler.

Both of which work perfectly well when left to run on Auto (ie come on set times of the day) but i can’t seem to “force” the boiler to be triggered early by pressing the +1 button/override. The programmer seems to be working ok - the light on it comes on, it shows that +1 (for example)has been pressed,but the boiler doesn’t respond.

Thanks

 

[D_Hailsham]

Has it always had this fault or is it something new?

 

[Merrily]

It has worked perfectly fine for 6 or so years, Just this last year I’ve noticed the problem

 

[D_Hailsham]

Have you tried resetting the programmer? (You will lose all your time-settings). I have attached the Installation Guide in case you don't have a copy. Go into Installer mode, then make a note of parameters 1 to 7 settings. Change Parameter 8 from 0 to 1. The programmer will revert to the default settings. Now change parameters 1 to 7 back to the settings you originally had. Check the result.

If this doesn't work you will probably need a new programmer.

 

[muggles]

The early ST9400Cs had an issue with a dodgy capacitor which didn't last as long as it should have done. A trick that sometimes works is to go into the installer settings and permanently disable the backlight - this sometimes gets the programmer up and running again. If not, you'll need a new one, but changing it is very simple provided you have 2 minutes spare and a small Philips screwdriver