Thermostat shows temperature that is clearly inaccurate compared to other thermometers.

Safety first: No hazardous work is required.

• Step 1 – Compare correctly: Place a reliable thermometer next to the thermostat for at least 30 minutes before comparing readings.
• Step 2 – Apply offset: Use the thermostat’s temperature offset or calibration setting to correct the reading by the measured difference.
• Step 3 – Seal wall opening: If cold or hot air leaks from the wall cavity behind the thermostat, remove the unit (power off first) and seal the cable entry hole with foam or putty.
• Step 4 – Relocate if necessary: If the thermostat is in a poor location (sun, drafts), move it to a more representative area.