2ND MAINTENANCE TUNE-UP FOR HEATING UNIT. CLEAN AND CHECK BURNERS AND BURNER OPERATION. CHECK MANIFOLD PRESSURE AND FOR PROPER VENTING. LUBRICATE ALL NECESSARY MOVING PARTS, AND ADJUST BLOWER COMPONENTS. CHECK THERMOSTAT, AIR FILTER, HUMIDIFIER, AIRFLOW, FAN CONTROL, HEAT EXCHANGER, HIGH LIMIT CONTROL, ENERGY CONSUMPTION, AND ALL ELECTRICAL CONNECTIONS.