CLEAN AND CHECK 17YR HEATING UNIT. CHECK ALL ELECTRICAL CONNECTION, HUMIDIFIER, MANIFOLD GAS PRESSURE AND FOR PROPER VENTING. CLEAN AND CHECK BURNERS AND BURNER OPERATION. LUBRICATE ALL NECESSARY MOVING PARTS AND ADJUST BLOWER COMPONENTS. CHECK HEAT EXCHANGER AND HIGH LIMIT CONTROL. CHECK THERMOSTAT, AIR FILTER, AIRFLOW, ENERGY CONSUMPTION.