You are spilling exhaust gases out of the draft hood.
It's not normal.
There are many possible reasons this could be happening.
If you post a wide angle picture of the entire vent run from the top of the water heater to the point where it exits the utility area (where the heater is installed) we may be able to suggest a possible cause.
Home Inspections, Infrared (Thermal Imaging) Leak Identification and Inspection Services, Roof, Attic, Building, Basement and Foundation Moisture Intrusion and Water Leak Inspections, Troubled Building Consultations - Serving Chicago and Suburbs To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.