A renovation changes air supply and draft

An atmospheric appliance operated in a large utility area before a renovation. New walls now enclose it in a much smaller space, and a powerful kitchen exhaust fan has been added nearby. The fuel piping and burner have not intentionally been changed. After the renovation, occupants notice intermittent odours during simultaneous operation, and a qualified worker observes combustion-product spillage under the prescribed assessment conditions. The appliance flame appears mostly blue. The customer asks whether the draft hood can simply be covered to stop the odour. Current appliance instructions, room layout information and the building exhaust details are available for the investigation.