whats that little dial inside a thermostat

[tinyhome]

I was always curious, inside my manual thermostat there is a little dial under the mercury. It has numbers on it and a little white metal arrow. it says 'longer time' and has an arrow. The little metal dial can be moved. Whats this about and how is it used? Ok thanks.

[coolwhip]

Its called an anticipator. The anticipator is a ring of resistive wire on the dial.

Heat Anticipator
This thermostat has a neat device called a heat anticipator. The heat anticipator shuts off the heater before the air inside the thermostat actually reaches the set temperature. Often, some parts of the house will reach the set temperature before the part of the house containing the thermostat does. The anticipator shuts the heater off a little early to give the heat time to reach the thermostat

[ralphtheplumber]

Good explanation, but you left out the most important part.

Don't mess with it.