Venting
26
GKNE-SVX001B-EN
5. Any run of single wall vent pipe passing through an
unheated space must be insulated with an insulation
suitable to 550°F (288°C).
6. The vent system must be installed to prevent collection
of condensate. Pitch horizontal pipes downward 1/4-
inch per ft. (21mm/m) toward the vent cap to facilitate
drainage. Vertical vent pipes should be piped as
depicted in
7. The equivalent length of the vent system must not be
less than 5-ft. (1.5m) and must not exceed 50-ft.
(15.2m). Equivalent length equals the total length of
straight pipe plus 10' (3.05m) for each 90° elbow and 4-
ft. (1.22m) for each 45° elbow.
8. Each slip joint must be secured with at least three
corrosion resistant screws. Two full turns of 3m #425
Aluminum Foil tape or its equivalent must then be
used to seal each joint. General Electric RTV-108, Dow-
Corning RTV-732 or an equivalent may be used instead
of the tape.
9. For horizontal vent systems longer than 5-ft. (1.5m),
the system must be supported from over-head
building structures at 3-ft. (1m) intervals.
10. The exhaust vent system must remain at a minimum
distance of 6-inch (152mm) from all combustible
materials. Any part of the vent system that passes
through a combustible material must be properly
insulated.
For a VERTICAL vent pipe section that passes through a
floor or roof, an opening 4-inch (102mm) greater in
diameter is required (see
). The opening must be
insulated and flashed in accordance with applicable
installation codes. See
.
A HORIZONTAL section of an exhaust vent system that
passes through a combustible wall must be constructed
and insulated as shown in
,
NOTICE
Increasing the clearance distances may be necessary if
there is a possibility of distortion or discoloration of
adjacent materials.
Figure 14. Vertical intake/Vent installation
* 2 FT. Min plus max snow depth for area.
** If excessive condensation develops, a drip leg with a
condensate drain may be required. Insulating the pipes may
eliminate the problem.
CAT-2764C
