Thermostat shows very high or very low indoor humidity readings that do not match other hygrometers.

Steps:

• Compare humidity: Use a separate hygrometer to compare humidity near the thermostat.
• Check location: Avoid installing the thermostat in bathrooms, near showers, or over humidifiers.
• Clean sensor vents: Remove the thermostat and gently blow out dust from the sensor vents with dry compressed air.
• Apply offset: If your Rheem thermostat supports humidity offset, adjust to match a known-good hygrometer.
• If readings remain extreme or stuck at 0%/99%: The humidity sensor is likely failed; thermostat replacement is recommended.