Water Heater Exhaust Location with Furnace and Masonry Chimney

I ran across this one recently and wanted to confirm this is an improper installation. The water heater (2006) is naturally vented natural gas rated at 40,000 BTU/hr. The furnace (1967) is naturally vented natural gas furnace rated at 105,000 BTU/Hr.

The age of the furnace is a different subject. The water heater vent is approximately 12" BELOW the furnace in a common 8 x 8 flue. I called it as a safety problem since the smaller BTU appliance should be located ABOVE the larger BTU appliance. Your Thoughts?



It should enter above. Correct.

Any time I see a hot water heater and/or a furnace venting into a chimney flue, especially when the flue runs through the center of a home, I recommend installation of a metal chimney liner/flue to the top of the chimney to keep gases from migrating through the mortar of the flue joints.