CAME OUT ON A SERVICE CALL, NO HEAT 10 PLUS.LV ISSUR, GAS VALVE NOT WORKING PROPERLY. INSTALL 3.5T FURNACE. SYSTEM WAS INSTALLED PROPERLY AND MADE SURE WORK AREA WAS LEFT CLEAN. CHECK BURNERS AND BURNER OPERATION. CHECK MANIFOLD GAS PRESSURE AND FOR PROPER VENTING. CHECK THERMOSTAT, AIRFLOW, AIR FILTER, HEAT EXCHANGER, HIGH LIMIT CONTROL, FAN CONTROL, AND ALL ELECTRICAL CONNECTIONS. CHECK BLOWER COMPONENTS. EVERYTHING IS RUNNING GOOD.