How to Calibrate a Honeywell Anticipator

Remove the Honeywell thermostat's cover. Place a level on the thermostat to make sure it is level. This is often performed when installing. If the thermostat is not level, the mercury switch may not function well.

Insert a pencil tip into the anitcipator's open triangle shaped point. Move it to set the anticipator to 1.2, which is at the far left on the scale. According to Honeywell, this is the right setting when using a heat-only thermostat.

Find the thermostat's primary rating stamped on the control nameplate if you are using the thermostat for air conditioning also. Change the anticipator setting to match the rating.

Connect an ammeter between the "R" and "W" terminals on thermostat's wall plate if you cannot find the rating. Turn on the heating for one minute. Read the ammeter. Change the aniticipator to the reading on the ammeter.

Insert a calibration wrench onto the hex nut under the anticipator foil. These are ordered separately from Honeywell depending on the thermostat's model. Hold the setting lever with your fingers and turn the wrench clockwise until the switch breaks contact. Remove the wrench.

Replace the thermostat's cover. Shift the setting lever to a low setting. Wait about
five minutes for the temperature to stabilize. Move the setting lever slowly until it reads the same as the thermometer.

Remove the thermostat cover again. Hold the setting lever with your fingers again.
Reinsert the wrench and turn it counterclockwise until the mercury rolls slightly to the left end of the tube. Set the thermostat system switch to the desired operation and replace its cover.