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4. VENTING, VENTILATION AND AIR INLET
A. GENERAL
Install vent system in accordance with Venting of
Equipment part of the National Fuel Gas Code, ANSI
z223.1/NFPA 54 or sections 7.2, 7.3 or 7.4 of CAN/CSA
B149.1, Natural Gas and Propane Installation Code.
WARNING
This vent system will operate with a positive
pressure in the vent pipe. Do not connect vent
connectors serving appliances vented by natural
draft into any portion of mechanical draft systems
operating under positive pressure.
WARNING
All joints of positive pressure vent systems must be
sealed completely to prevent leakage of flue products
into the living space.
NOTICE
Flue gases will condense as they exit the vent
termination. This condensate can freeze on exterior
building surfaces which may cause discoloration of
these surfaces.
B. WALL THIMBLE (SIDEWALL
VENTING ONLY)
1. Determine vent cap (terminal) location.
a. Must be within the maximum and minimum vent
and air intake lengths shown in Tables 4.1 and 4.2.
b. Maximum wall thickness for the 19-1/2" (495 mm)
long Wall Thimble (standard) is 11-1/2" (292 mm).
Maximum wall thickness for the optional 28" (711
mm) long thimble is 20" (508 mm).
Figure 4.1: Wall Thimble
VENTING, VENTILATION AND AIR INLET
c. Provide 2" (51 mm) clearance between vent pipe
and combustible construction. No clearance is
required between Thimble and combustible
construction.
d. Provide 3 feet (1 meter) clearance above any
forced air inlet within 10 feet (3 meters).
e. Provide 1 foot (0.3 meters) clearance below and 1
foot (0.3 meters) beside, or 1 foot (0.3 meters)
above any door, window, or gravity air inlet into
any building.
f. Provide 1 foot (0.3 meters) clearance between
bottom of vent terminal and ground level and
normal snow lines.
g. Provide 4 feet (1.2 meters) horizontal clearance
from electric meters, gas meters, regulators and
relief equipment. In Canada, this dimension must
be 6 feet (2 meters).
h. Do not locate vent terminal over public walkways
where condensate could create a nuisance or
hazard.
i. When adjacent to a public walkway, locate vent
terminal at least 7 feet (2.1 meters) above grade.
j. Do not locate directly under roof overhangs to
prevent icicles from forming.
2. Cut a 5-1/8" (130 mm) square hole in sidewall to
allow Peerless
®
Wall Thimble to go through.
3. Insert Thimble from inside wall with 4" (102 mm)
diameter air inlet connection facing down. Extend
Thimble 3-1/2" (89 mm) past outside wall surface.
The cut-out opening of thimble is pointed down.
4. Use a minimum 2-1/2 foot (762 mm) piece of 3"
(76 mm) diameter AL29-4C stainless steel vent pipe
for insertion through Wall Thimble. See Vent Pipe
section below for vent pipe requirements.
9
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