Combustion Air next to exhaust vent in a closed system

Does the exhaust and combustion air really need to be separated? Just trying to think about how this could be a problem in a closed 90% furnace. Smaller ones are from the furnace larger one is power vent water heater.

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Check the manufacturers install guidelines. Either way thats too close, especially below that protrusion directly above (Bay or bow window?)


Terrill, when I had my, low to the ground, concentric vent changed to 2 vents, one intake and one exhaust, there were very specific measurements separating the two vents in the manufacturer’s installation instructions and they differed from the other manufacturers. I had it changed because the concentric vent got blocked by snow and shut down in the cold 7 PM of a wintery night and I had to figure what happened out fast as the temperature kept dropping fast. I finally saw the buried vent and dug it out and the furnace kicked on.

So, I would recommend Googling the make and model installation instructions and see what they say to get an accurate answer to your question.

Good luck and Happy Inspecting!! :smile:

concentric vent:


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Thanks, its a Carrier. I’ll check.

The things we deal with here in the North eh Larry:grin:

Isn’t that the truth, Scott! :smile: