National Oilheat Research Alliance 19
4. Each joint of the flue pipe shall be fas-tened
with at least three screws.
5. The flue pipe must not be longer than 75
percent of the portion of the chimney above the
chimney inlet. (For example, if the chimney
extends 20' above where the flue pipe
connects, the flue pipe can be no longer
than 15'.)
6. In masonry chimneys, the flue pipe
must extend through the chimney wall
to the inner face or liner, but not beyond,
and shall be firmly cemented in place.
7. The flue gas exit of a chimney must
be at least three feet above the highest
point where it passes through the roof
and at least 2' higher than any portion
of a building within 10' of the chimney.
Figure 16.
Figure 15
Figure 16