CLEAN AND CHECK 17YR HEATING UNIT. CLEAN AND CHECK BURNERS AND BURNER OPERATION. CHECK MANIFOLD GAS PRESSURE AND FOR PROPER VENTING. CHECK HEAT EXCHANGER AND HIGH LIMIT CONTROL. CHECK THERMOSTAT, AIR FILTER, AIRFLOW, HUMIDIFIER, ENERGY CONSUMPTION, FAN CONTROL, AND ALL ELECTRICAL CONNECTIONS. INSTALLED 2T 3 P 12Y P&L. MADE SURE EVERYTHING WAS INSTALLED PROPERLY AND WORK AREA WAS CLEAN WHEN FINISH.