13 POINT MAINTENANCE TUNE-UP FOR 3YR UNIT. CLEAN AND CHECK BURNERS AND BURNER OPERATION. LUBRICATE ALL NECESSARY MOVING PARTS, ADJUST BLOWER COMPONENTS. CHECK THERMOSTAT, AIR FILTER, HEAT EXCHANGER, HIGH LIMIT CONTROL, HUMIDIFIER, AND ALL ELECTRICAL CONNECTIONS. CHECK MANIFOLD GAS PRESSURE AND FOR VENTING, CHECK FOR PROPER ENERGY CONSUMPTION.