CH Frost Stat, Dial fell off

[dougsdir24]

A couple of weeks ago when messing aroundin my garage i accidentally knocked off the dial on my CH frost stat, I stuck it back on (Unsure of what way it was meant to go back on). But since then Ive noticed the boiler coming on at odd times when the HW and CH is switched off. I can only assume I altered the setting somehow but im not sure how the dial is meant to be positioned, its not very clear.

I have taken a photo of the stat and the dial :

someone explain how its meant to be positioned?

Ta

Douglas

[Dave Liquorice]

That looks like a Honeywell frost stat. The knob with numbers on is normally under a fixed cover to prevent casual tampering. This fixed cover also covers those exposed terminals. Not having the terminals covered is just a tad lethal, there will be live mains there at all times. I can't envisage how you can knock the knob off if you have the cover unless you really gave the stat some welly and destroyed the cover as well. If you don't have the cover, I suggest that getting a replacement frost stat is the best and safest option.

[John Rumm]

Can you turn the stat to one end of its travel, and then mount the knob so that it is also at the same end of the scale. That ought to get you close ish.

[dougsdir24]

Yeah its a Honeywell frost stat, I have the cover and it is normally on, i just removed the cover so i could take the pictures. No need to panic ;) The dial just has a circular section that snaps onto the stat, there are no other guides to lock it into a certain position. :(

[meow2222]

If it still works, wait till the temp there is the temp at which you want it to switch, and slowly adjust it until it clicks, then its set. Put the knob on, pointing to wherever you want it to oint to. BUT some of these stats have a live spindle, so caution is needed re adjusting and refitting. Test if live first - you can adjust it just as well with the power off.

NT

[Dave Liquorice]

I've just been out to the barn and looked at mine. Unfortunately that won't work, the end stops for the mechanisium are provided by the webs in the back of the knob hitting a projection on the stat. The splined mounting knob will rotate past the points where the knob would stop it. I suspect if you got a to keen on turning the splined mount you'd damage the bellows...

I can only suggest slowly rotating the splined knob until the stat clicks, probably counter clockwise if the current temperature is above were the stat would operate to call for heat. Then put the knob back on such that the current temp is at the top, the index point is between the two rows of holes arranged in arcs. You do need to know the current temp.