Gunnar,

In our area, we need to have two separate, dedicated vents/ducts for combustion air into an enclosed room with non-direct vent combustion appliances. One vent down low and one high. Two high or two low vents won't perform as intended. I have talked myself silly trying to convey this to HVAC contractors.

DavidR - Are you referring to carbon monoxide (CO) or carbon dioxide (CO2)?

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Eric Barker
Moraine Woods Consulting, Inc.
Barrington, IL