The thermostat displays a temperature that is clearly too high or too low compared to the actual room temperature.

Safety: No high-voltage work is required.

• Step 1 – Compare readings: Place a reliable thermometer near the GLAS and compare the readings over 30 minutes.
• Step 2 – Check location: Ensure that the GLAS is not located above supply vents, near exterior doors, in direct sunlight, or above electronics that emit heat.
• Step 3 – Improve wall insulation: Remove the GLAS and check for a large hole in the wall behind the wall plate. Seal any gaps with foam or putty to prevent wall cavity drafts from affecting the sensor.
• Step 4 – Relocate thermostat: If the location is inherently poor, consider moving the GLAS to an interior wall in a representative room. This may require running a new thermostat cable.
• Step 5 – Replace thermostat: If the location and environment are good but the readings remain significantly off, the internal temperature sensor may be faulty. Replace the GLAS thermostat.