Furnace runs but gas bill is unusually high and runtime seems excessive.

Steps:

• Replace filter: Ensure unrestricted airflow through a clean filter.
• Thermostat settings: Lower setpoint a few degrees and use programmable schedules to reduce runtime.
• Inspect ducts: Seal visible duct leaks in basements or attics with mastic or foil tape.

Note: A home energy audit or HVAC evaluation can identify sizing or insulation issues.