Check thermostat calibration. Inaccurate thermostats affect comfort and operating costs.
Replace air filters or air cleaner media. Clean filtering media prevents furnace overheating. It also ensures adequate airflow for comfort and improved air quality within the occupied space.
Check blower motor brackets for breaks or cracks. Vibration and unbalance can weaken and break brackets causing damage to the furnace.
Check setscrews on blower wheel for tightness and centered in housing. Setscrews sometimes work loose and cause misalignment resulting in poor airflow and eventually damage to the blower.
Check blower wheel for excessive dirt; wash blower wheel and housing if necessary. Dirt builds up in the blower wheel vanes and restricts airflow, causing poor efficiency in the system.
Lubricate motors and bearings if applicable. Motor life can be extended with proper lubrication.
Check condensate drain for blockages on condensing gas furnaces. Clogged drains result in overflowing, which causes damage to equipment and building. Some furnaces will lockout when the drains become clogged leaving you without heat.
Check combustion air blower. Examining the blower wheel for rust, corrosion, and blockages can allow for early repairs before it becomes an emergency.
Check for gas leaks. Vibration can loosen some fittings and joints.
Check for spider nests in air shutters & burner openings. Spiders love gas appliance air passages for some reason. They frequently build nests which block combustion air from allowing burners the proper amount of air for combustion.
Check main burners for deterioration, blockage, or corrosion. A defective burner can cause carbon monoxide gas and premature heat exchanger failure.
Check flue and combustion air piping for blockages and breaks. Frequently, nests from insects and rodents are found in the pipes. Occasionally, ice will build up in cold damp weather where condensing furnace pipes exit the building. Blockages can cause furnace shutdown and even damage the furnace.
Check flame sensor signal. Corrosion, positioning, and poor grounding of flame sensor can weaken flame signal and cause nuisance safety lockouts.
Check gas pressure and adjust if necessary. High gas pressure will cause heat exchanger failure, sooting, and furnace overheating. Low pressure will cause inefficient and erratic operation.
Check for proper control operation. Inoperative safeties are a fire hazard.
Check for flue gas leakage into living space. Even small amounts of leakage into the occupied space can cause headaches and an ill feeling.
Check condensate drain tubing on condensing furnaces for leaks & cracks. Condensate is acidic and will corrode any metal it touches requiring early furnace replacement
Inspect the exterior of equipment and replace any missing screws to prevent air leakage. As much as 25% of conditioned air can escape due to improperly fitted or secured access panels.
Check furnace overall operation.