His daughter told me she thinks he just likes to tinker with things too much and keeps turning the dial up and down and won’t leave it alone.
In which case a dollar to a pinch of snuff he's probably had the thing to bits already to see how it works! I have seen these things 'recalibrated' by mispositioning of the dial gear-ring relative to a central pinion.
I've found thermostats to be notoriously inaccurate in controlling actual room temperatures - the vital thing is to have them positioned in the right place. Put the stat in a 'cold spot' in the room and it will always lag the actual temperature.
No need to wait hours for a test, just use a standard thermometer reading, after a few minutes to stabilise, then test the stat by your 'click' test- quite accurate enough to see if it really is 10 deg out.
Since time is money, I'd change it anyway for the one on your desk, he sounds like a fusspot.
Alan
