Honeywell ST9400C 7 Day Programmer All aspects of plumbing questions and answers, help, tips and information

[Hansel]

I have a Honeywell ST9400C 7 day programmer & have realised it is coming on at times prior to those I have set on the timer. I now realise this must be to do with the Installer parameters.

I have tried to follow the instructions:
To Enter Installer Mode:a. Ensure the slider is in the RUN position, then press ok & minus buttons and hold together for 8 seconds. Ignore the 'NOT VALID' message that is displayed for a few seconds.

The message 'SET UP MENU' will show briefly, followed by 'SETINSTALLER OK ?' which are easy enough to change, BUT after the NOT VALID message, I am not getting the SET UP MENU & cannot proceed.

Please can anyone assist?

[ericmark]

I do not remember any problem setting the programmer, I know modern units you can set the time you want the room to be warm by, but the ST9400C is a rather old unit, which one would not fit today.

Today rather than on/off we set different temperatures for different times of the day, this was basic because of the demise of the tungsten bulb, which would make the room feel warmer in the evening, even when air temperature was the same, So today we use a combined thermostat and programmer.

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[Hansel]

Thank you. That's slightly worrying that it's an old programmer - it was only fitted in May this year! Unfortunately that doesn't really answer my question as setting it is easy enough. The problem is that having set it, it comes on when it isn't supposed to. The issue is not being able to access the installer settings to override them, which is why I believe mine is coming on before it's set to. The instructions in the handbook don't work in practice.

[Mr White]

I searched and I found videos of how to programme your programmer dating back 12 years ago, so yes the design is old, but you can still buy them today.