Re: How to adjust honeywell round thermostat (mercury switch) to the right temperature

Agree with you and Ransley.   First thing is to make sure it's
level.   Then if necessary you need a thin wrench that you can hold
the nut with so the mechanism doesn't move while you rotate the dial.

All in all, considering the conveniences of a programmable digital
one, I'd just replace it.   Wouldn't it be nice to set the heat back
at night and have it come back up shortly before you wake up?

I don't have that particular unit, but on mine, it looks like the is a nut
behind the metal thermo spring that could be turned a bit to calibrate it. What
you need is to turn it in the direction that makes the mercury switch less
level - just a little. If such an adjustment is not evident, bending the metal
where the switch attaches to the thermospring could do it.

The copper pointer at the bottom probably adjusts the difference between turn on
and turn off.

How do I adjust a thermostat so that the heat reaches the set temperature?

My Honeywell round thermostat has a bulb with mercury in it and a coil of
metal that seems to control when it makes electrical contact.

When I set the Honeywell bulb thermostat to 68°F, the heat only gets to
about 58°F. Likewise, when I set the thermostat to 85°F, the heat shuts off
when it reaches about 75°F.

This works fine except my husband keeps yelling at me for setting the
thermostat to 85°.

I know the simple answer is to change him but why do thermostats have
numbers on them if they're not even close to those numbers?

Is there a way to adjust the temperature? When I pull the round cover off,
I see a copper pointer on the bottom with etch marks on the plate below but
that pointer is already all the way to the left and moving it to the right
just seems to make the offset error worse.

What's the procedure to adjust a Honewell round thermostat to reach the set
point before turning off?