SECOND CLEAN AND CHECK HEATING UNIT THAT IS 12YR, UNDER SERVICE AGREEMENT. CHECK MANIFOLD GAS PRESSURE AND FOR PROPER VENTING. CLEAN AND CHECK BURNERS AND BURNER OPERATION. CHECK THERMOSTAT, AIRFLOW, AIR FILTER, HEAT EXCHANGER, HIGH LIMIT CONTROL, HUMIDIFIER, ENERGY CONSUMPTION, AND ALL ELECTRICAL CONNECTIONS. CLEAN AND CHECK BURNERS AND BURNER OPERATION.