Unknown Flue Pipe

[Stephen G Sheldon]

In a house built in 2001 there is a gas furnace that is properly connected, but to the side of it is are two larger flue pipes (only one is shown in the picture) vented through the ceiling but which are open on the bottom. Can anyone comment on what this may be about?

[Jerry Peck]

Combustion air as that space was a "confined space" and those vents were installed to make up the difference.

One should be within 12" of the ceiling (that one looks more than 12" down) and one should be within 12" of the floor.

Size also matters as those are required to be 100 square inches minimum - what diameter were those vents? Need to be 12" minimum diameter for 100 square inches.

[Stephen G Sheldon]

jerry,

Thank you. That makes alot of sense now that I think about it.