Zero Clearance Wood Fireplace
NateMeredith
| Posted in Energy, Heating & Insulation on
One of my customers subscribes to TOH, which I can’t figure, I give her my FHB to read. Oh well… Anyway, I saw an article about zero clearance woodburning fireplaces that look to be using B vent. Does anyone know anything or have any experience? I don’t remember the name of the company, and recycling day has passed so the mag is gone. Just curious, I never heard of such an animal.
Nate
Replies
Inserts that are rated as a gas fired appliance may use Type B. vent. In some jurisdictions you can use Type B vent with a masonry fireplace if you post a PERMANENT notice that the fireplace cannot be used with solid fuels (wood or coal, etc.) I just did a vent design for a two sided fireplace in a hotel here in Denver with B vent. You have to be careful about sizing. I recently was an expert witness in a case where the fireplace contractor went to a local B-vent distributer and gave him the rating of the logs to size the vent. It was sized as if for a furnace or boiler, 8" instead of 18" for a fireplace. You have to size for the dilution air and a face velocity of 48 fpm (ASHRAE Handbook of Fundamentals 1997). I'm collecting quite a few horror stories. Hey Andy need an article??
I recall that the article (it was really more of a small product description) referred to a double wall vent, and I am the one who labeled it b-vent. This was a manufactured fireplace that burt real wood, and the vent came out the top and went up through a chase through the roof. Do you have any insight on this appliance? Though I don't remember the name of the manufacturer, I do recall that there was only one company making this type of unit. Thanks for the feedback.
Nathan
Double wall vent could refer to B-Vent but if it was for a wood burning fireplace it would be High temperature manufactured chimney sometimes called Class A. B-vent has a maximum temperature rating of 450 F. High temperature vent has variuos ratings but the minimum is 1100 F continuous and up to 1400 F for one hour I think.