CLEAN AND CHECK 6YR HEATING SYSTEM. CHECK AIRFLOW, AIR FILTER, THERMOSTAT, HUMIDIFIER, HIGH LIMIT CONTROL, THERMOSTAT, ENERGY CONSUMPTION, FAN CONTROL, GAS PRESSURE, AND ALL ELECTRICAL CONNECTIONS. CLEAN AND CHECK BURNERS AND BURNER OPERATION. LUBRICATE ALL NECESSARY MOVING PARTS, AND ADJUST BLOWER COMPONENTS.