In order to calibrate a Honeywell digital thermostat, check the thermostat's accuracy with a tube thermometer, make sure the thermostat is clean inside the face plate, and make sure that the thermostat is level with the ground. If the thermostat is not reading the correct temperature, contact Honeywell to have an expert inspect it.Continue Reading
Use the following steps to calibrate a Honeywell thermostat.
Leave a tube thermometer next to the thermostat to determine how far off the thermostat's reading is.
Open the faceplate and make sure all components are dust-free.
Some thermostats use mercury to check the temperature. Make sure the thermostat is level with the ground. If the thermostat still does not read the correct temperature, it may need to be replaced.