Thermostat shows 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 GLAS and compare readings over 30 minutes.
• Step 2 – Check location: Ensure GLAS is not above supply vents, near exterior doors, in direct sunlight, or above electronics that emit heat.
• Step 3 – Improve wall insulation: Remove GLAS and check for a large hole in the wall behind the wall plate. Seal 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 new thermostat cable.
• Step 5 – Replace thermostat: If location and environment are good but readings remain significantly off, the internal temperature sensor may be defective. Replace the GLAS thermostat.