Heating performance tune up times one system. Change out filter client supplied. Inspect blower, evaporator and ductwork. Test all safety features High limits and roll outs. Tightened all wire connections. Check gas pressure. System has 3.5 in of water column. Check heat exchanger for cracks found none. No carbon monoxide or gas leak detected in home. Test thermostat for proper operations. System operating at manufacturer specs at this time.