CLEAN AND CHECK 5YR HEATING UNIT. CHECK GAS PRESSURE AND FOR PROPER VENTING. CHECK THERMOSTAT, AIR FILTER, HUMIDIFIER, ENERGY CONSUMPTION, HEAT EXCHANGER, HIGH LIMIT CONTROL, FAN CONTROL, AND ALL ELECTRICAL CONNECTIONS. CLEAN AND CHECK BURNERS AND BURNER OPERATION. LUBRICATE ALL NECESSARY MOVING PARTS, AND ADJUST BLOWER COMPONENTS.