Arrived at location on 10/11/21 - Arrived to location and spoke to Dave. Checked incoming supply pressure and found it was 5.0 in/wc. Adjusted main regulator at tank until unit had 10.0 in/wc. Lit unit and ran for 20 minutes. Flames were blue and seen no soot leaving unit. Recommended that supply reg from tank be replaced. Dave stated that he will order and replace regulator himself. Unit back in service.