vent to chimney column

[Jim Baird]

B vent connector enters chimney column with fireplace flue.

From 06 IRC,

G2427.10.13 (503.10.13) Fireplaces. A vent connector

shall not be connected to a chimney flue serving a fireplace

unless the fireplace flue opening is permanently sealed.

This vent connector enters bottom of massive chimney column. I can't tell whether there are two flues or a B vent contained inside the column. At fireplace opening the effluent exit is audible when furnace operates.

Does this code section prohibit this arrangement?

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[Jim Katen]

Audible would be good enough for me to call it wrong.

Are you sure that they didn't run the vent connector into the ash dump?

[Hearthman]

To have a heater flue or vent sharing a chimney with a fireplace would require two separate flues separated by a 4" wythe. They may have lined the heater flue with B-vent or a listed liner but the requirement for separation remains. The section quoted applies where the open hearth fireplace is to be discontinued and closed off so it can be used for the heating appliance. You can never under any circumstances have any type of appliance share the flue with a fireplace. If you cannot determine the requisite separation the recommend a level II inspection.

FYI, B-vent cannot be permanently cemented into the base of the chimney. It would have to be inserted into a thimble or sleeve that allowed removal for inspection.

[Jim Baird]

Thanks for the replies.

The chimney column was wide enough to contain two flues, but its terminal was so high I could not see the top, which also had a pretty good wrapping type of weather hood.

I think the current occupants likely resumed the fireplace use long after a former occupant sealed it off in order to put the furnace in and vent it that way.