Director's Order FS-051-04 - Existing B-Vent Not Certified for Exterior Applications.
Order FS05104
*Click image to enlarge. This Order is replaced by the Gaseous Fuels Code Adoption Document FS-212-14 (B149.1-10) and FS-225-17 (B149.1-15) as Annex N.
Download the FS-212-14 Amendments -
Here