dtontarski Posted December 14, 2014 Report Share Posted December 14, 2014 Observed what appeared to be B-vent (no legible labeling) running up the exterior wall of a home in Northern New York. This vents 4-small atmospheric venting appliances. I know that this is not recommended due to drafting and condensation issues, and I generally see exterior run B-vent installed in an exterior wall chase. My question - Are there metal vents other than B-vent that would allow this? What prompts my question is several other bordering homes had similar set ups. Click to Enlarge 63.76 KB Click to Enlarge 63.65 KB Quote Link to comment Share on other sites More sharing options...
Bill Kibbel Posted December 14, 2014 Report Share Posted December 14, 2014 I don't know of any other gas vent system that would be acceptable for that installation. Maybe there's an insulated vent that's available, but someone (M.E.) would have to approve it. What's in the pic is a B-vent. In addition to support and possible sizing issues, I would tell them that any more than 5' exposed requires an unvented enclosure or chase that has a minimum of R-8 insulation. Quote Link to comment Share on other sites More sharing options...
Marc Posted December 14, 2014 Report Share Posted December 14, 2014 Wouldn't an HT vent be acceptable for outdoor applications? Just size it properly and open that wallet wide. Marc Quote Link to comment Share on other sites More sharing options...
dtontarski Posted December 14, 2014 Author Report Share Posted December 14, 2014 Thanks for the responses. I had never checked out HT vent before..... "woven ceramic fiber refractory blanket - surrounded by two inner walls" Yes this might just draft alright in this climate. I don't think I could get my wallet to open that wide....thanks for referencing though....good to know about. Quote Link to comment Share on other sites More sharing options...
Jim Katen Posted December 14, 2014 Report Share Posted December 14, 2014 Wouldn't an HT vent be acceptable for outdoor applications? Just size it properly and open that wallet wide. Marc B-vent is "acceptable" for outdoor applications, there's just no prescriptive guideline for using it outdoors below the roofline. I'm not at all sure that A-vent (what you can HT) is any more acceptable in that location when used with a gas appliance. Quote Link to comment Share on other sites More sharing options...
dtontarski Posted December 14, 2014 Author Report Share Posted December 14, 2014 I wrote this B-vent installation up as "not recommended" as installed, and specified why. I additionally recommended that this be further evaluated when the HVAC professional is called in to further evaluate the heavy corrosion near the draft diverters of the 2-28 year old forced air furnaces and their 28 year old air filters. Quote Link to comment Share on other sites More sharing options...
Brandon Whitmore Posted December 14, 2014 Report Share Posted December 14, 2014 This is what Selkirk has to say: B vent See #5 Quote Link to comment Share on other sites More sharing options...
dtontarski Posted December 15, 2014 Author Report Share Posted December 15, 2014 Jim - "9000 posts" I can't thank-you enough for your contributions to this forum! Happy Holidays! Dave Tontarski Quote Link to comment Share on other sites More sharing options...
plummen Posted December 16, 2014 Report Share Posted December 16, 2014 Ive seen plenty of b-vent ran on the outside of houses over the years,never seen a city inspector tag it. Quote Link to comment Share on other sites More sharing options...
Mike Lamb Posted December 16, 2014 Report Share Posted December 16, 2014 If it has been used for awhile I would expect moisture and rust especially at connections. Duravent has in-chase guidelines and drawings for exterior lengths in cold climates. Quote Link to comment Share on other sites More sharing options...
Tom Raymond Posted December 16, 2014 Report Share Posted December 16, 2014 My house has a b vent flue exposed like the OP, 24' of vertical. I took the top 2' off when I did the roof a month ago. It was completely blown, acid eroded inside and rusted nearly through outside. The section below is fine. I have IR images of it somewhere. Mid 20s ambient, mid 60s pipe temps, upper 70s at the joints. Quote Link to comment Share on other sites More sharing options...
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