Sterling QVSB - Manual (Page 13)

13
INSTALLATION - VENTING
(continued)
5. Any run of single wall vent pipe passing through an
unheated space must be insulated with an insulation
suitable to 550°F.
6. The vent system must be installed to prevent col-
lection of condensate. Pitch horizontal pipes down-
ward 1/4 inch per foot (21mm/m) toward the vent
cap to facilitate drainage. Vertical vent pipes should
be piped as depicted in Figures 11 & 12.
7. The equivalent length of the vent system must not
be less than 5 feet (1.5m) and must not exceed 50
feet (15.2m). Equivalent length equals the total
length of straight pipe plus 15 feet (4.6m) for each
90° elbow and 5 feet (1.5m) 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 feet
(1.5m), the system must be supported from over-
head building structures at 3 foot (1m) intervals.
10. The exhaust vent system must remain at a minimum
distance of 6 inches (152mm) from all combustible
materials. Any part of the vent system that passes
through a combustible material must be properly
insulated.
NOTICE: Increasing the clearance distances may be
necessary if there is a possibility of distortion or
discoloration of adjacent materials.
For a VERTICAL vent pipe section that passes through
a fl oor or roof, an opening 4 inches (102mm) greater in
diameter is required. The opening must be insulated
and fl ashed in accordance with applicable installation
codes.
A HORIZONTAL section of an exhaust vent system that
passes through a combustible wall must be constructed
and insulated as shown in Figures 13 & 14.
11. The top of a VERTICALLY VENTED exhaust system
must extend at least 3 feet (1m) above the roof
surface that it passes through. The point of
termination for a HORIZONTALLY VENTED exhaust
system must be at least 12 inches (305mm) from
the exterior of the wall that it passes through. In
addition, the termination point must be at least 3
feet (1m) above grade or above the snow line, more
than 6 feet (2m) from the combustion air inlet of
another appliance, more than 3 feet (1m) from any
building opening and more than 4 feet (1.3m) from,
and not directly above, any gas meter or service
regulator, refer to Figures 13 & 14.
Figure 11 - Vertical Intake/Vent Installation
* Size according to expected snow depth
** If excessive condensation develops, a drip leg
with a condensate drain may be required.
Insulating the pipes may eliminate the
problem.