13 POINT MAINT. ON 7YR HEATING UNIT. CLEAN AND CHECK BURNERS AND BURNER OPERATION. CHECK MANIFOLD GAS PRESSURE AND FOR PROPER VENTING. CHECK HEAT EXCHANGER AND HIGH LIMIT CONTROL. LUBRICATE ALL NECESSARY MOVING PARTS, AND ADJUST BLOWER. CHECK THERMOSTAT, AIR FILTER, FAN CONTROL, AIRFLOW, ENERGY CONSUMPTION, HUMIDIFIER, AND ALL ELECTRICAL CONNECTIONS.