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Author Topic: Director's Advisory FS-065-05 - Interior Type-B Vents and Metal lined chimneys  (Read 2538 times)

Offline Admin

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Vent Sizing and Resizing for Interior Type-B Vents and Metal lined chimneys.

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Clause (8.13.1) - A vent or chimney serving a single appliance shall provide effective venting and shall be sized
(a) so that its effective area is not less than that of the draft-control device outlet or the flue outlet; or
(b) in accordance with good engineering practice, such as by the use of
  (i) Table C.1, C.2, C.5, or C.6 of Annex C for a draft-hood-equipped or a fan-assisted Category I appliance; or
  (ii) engineered venting tables acceptable to the authority having jurisdiction.

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Annex C (C.2.2) - The vent tables included in this Annex apply to vents and chimneys internal to the structure below the roof line. Exterior chimneys or vents not enclosed by the structure or a chase below the roof line can experience continuous condensation, depending on locality. A chimney with one or more sides exposed to the outside of the structure shall be considered to be an exterior chimney. A Type B vent or a certified chimney lining system passing through an unused masonry chimney flue shall not be considered to be exposed to the outdoors. The DP column shall be used to determine the capacity of a venting system within a building constructed in accordance with Clause 8.2.1.

Download Director's Advisory FS-065-05 - Here

Offline Hgye

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Is this Director's Advisory still valid?

Offline Admin

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Yes, it's just to clarify Clause 8.13.1.

Offline mattmctree

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I see countless unit heaters vented through the roofs of ware houses and buildings with b vent. Is this against code or am I misunderstanding the

Offline Admin

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If it's interior B-Vent installed inside the building there should be no problem.  Most unit heaters can still use B-Vent for vertical venting.  I believe since 2012 you need to use stainless steel venting for horizontal venting.