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