格雷格·哈夫（Greg Havel）的文章和照片
During the 1800s and in the early 1900s, masonry chimneys for kitchen ranges and space heaters were often built on wood brackets or shelves attached to wood stud walls. This method saved the cost and labor of installing the “extra” masonry from the foundation to a point halfway between floor and ceiling. When these chimneys were no longer needed, the stove-pipe openings were closed with decorative tin plates. Many of these chimneys are still present in older homes and other buildings, even though they have been concealed by remodeling and reroofing projects.
在现代的轻质木制建筑中，壁炉和燃木机构的烟囱再次得到木材框架的支撑。尽管制造的双壁或三壁金属烟囱比砌体烟囱轻一些，但其支撑也是如此。照片1显示了一个双壁金属烟囱的一部分，并在烟囱穿过地板天花板组件或屋顶下方使用一个支撑法兰。如今，这些地板天花板和屋顶组件通常由轻巧的制造木材产品（如i-o-tosist和木桁架）提供支持。
（1）
Note that the interior pipe for combustion products is supported from the outer pipe by thin strips of sheet metal and rivets, as shown in photo 1. This space between the inner and outer pipe is open at the bottom of the chimney and is vented separately from the combustion products by a cap above the roof (photo 2). Convection in this space keeps the outer pipe comparatively cool and unlikely to ignite surrounding wood framing if the chimney is installed with the clearances required by the chimney manufacturer and by National Fire Protection Association 211烟囱，壁炉，通风孔和固体燃料燃烧器具。
（2）
These manufactured metal chimneys are usually installed inside wood-frame chimney enclosures that extend from the floor at the fireplace or wood-burner, up through the roof. They may also be installed through exterior walls and exposed to a point above the roof. Photo 3 shows steel-stud framing for a chimney enclosure for a fireplace with a support flange near the top of the photo. This enclosure extends above the roof and appears as a rectangular box finished with siding to match the rest of the house, with the vent cap on top. These enclosures may also be clad with other materials, including brick or stone masonry, supported by the roof trusses and wall framing.
（3）
- 如果它们用于比评分的温度更高的温度，
- if modifications are made during installation of the chimney,
- if the chimney sections are not connected properly or if pipe sections from more than one manufacturer are used,
- 如果在烟囱和可燃的建筑材料之间未保持适当的间隙，
- 如果他们没有得到适当的支持，并且
- 如果没有定期清洁。
互联网搜索具有典型的安装图，搜索制造商网站的“双壁烟囱管”和“三重壁烟囱管”，符合NFPA和ANSI/UL标准。
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