VENTING
13
A. GENERAL
1. Install vent system in accordance with the “Venting
of Equipment” Chapter of the
National Fuel Gas
Code
, ANSI Z223.1/NFPA 54, the “Venting Systems
and Air Supply for Appliances” Section of the
CAN/CSA B149.1,
Natural Gas and Propane
Installation Code
. or applicable provisions of the
local building codes.
2. Do not connect vent connectors serving appliances
vented by natural draft into any portion of
mechanical draft systems operating under positive
pressure.
3. Refer to the following venting options to determine
which method is applicable.
ON –
B. CHIMNEY VENTING
If venting into a masonry chimney; chimney must be
lined with a fire clay tile liner or corrosion resistant metal
liner. Type B vent may also be used as a lining system or
as a stand alone chimney vent.
1. The vent system, when installed per the following
instructions, will operate with a negative pressure (draft).
2. Horizontal portions of the vent pipe shall slope
upward
from the boiler towards the vertical vent not
less than 1/4" per foot (21 mm per meter). Support
horizontal portions of the venting system to prevent
sagging by use of metal strapping or equivalent
means. Locate supports at no more than 4 foot (1.2
meter) intervals.
Parties horizontales de l'évent doit pente ascendante
de la chaudière vers la cheminée verticale d'au
moins 1/4 "par pied (21 mm par mètre). Fournir un
support à toute portion horizontale du système
d’évacuation à l’aide de courroies de metal ou une
méthode équivalente afin de l’empêcher de
s’affaisser. Placer les supports à des intervalles ne
dépassant pas cent vingt deux (122) centimètres (4
po), ou en suivant les recommandations d’
installation du fabricant.
3. Locate fan adapter, silicone, hardware and fan
adapter gasket in boiler miscellaneous parts box
and attach to blower outlet flange. Refer to Fig. 4.1
for details.
4. Apply 1/4" (6 mm) bead of silicone around fan
adapter and slip increaser over the fan adapter. Refer
to Table 4.1 for increaser and chimney sizes.
Increaser to be provided by installer.
5. Single wall vent pipe should be furnished between
increaser and chimney. If the vent connector shall be
located in or pass through a cold area, the vent
connector shall be type B material.
C. DIRECT EXHAUST; HORIZONTAL
VENTING
1. This vent system will operate with a positive pressure
in the vent pipe. Follow vent pipe manufacturers
instructions for proper assembly of vent pipe and
fittings.
2. Refer to Table 4.2 for minimum and maximum vent
length allowed.
3. Maintain a minimum 2" (51 mm) clearance between
vent pipe and combustible construction for an un-
enclosed vent. See vent manufacturer instructions for
minimum clearance to an enclosed vent.
4. When installing vent pipe through a combustible
wall, pipe must pass through a metal wall thimble;
maintain a 2" (51 mm) clearance between vent pipe
and thimble. Follow thimble manufacturer’s
instructions. Seal between thimble and exterior wall
using exterior-rated caulk or silicone to prevent water
damage and also to prevent recirculation of flue
products into the structure.
5. Determine vent terminal location.
a. Vent terminal shall be located at least 3 feet (1
meter) above any forced air inlet located within
10 feet (3 meters).
b. Vent terminal shall be located at least 4 feet (1.2
meters) below, 4 feet (1.2 meters) horizontally
from, or 1 foot (0.3 meters) above any door,
window, or gravity air inlet into any building.
c. Vent terminal shall be located at least 1 foot (0.3
meters) above ground level or normal snow lines.
See subsection 7 below if terminal needs to be
extended above ground level or snow line.
4. VENTING
Table 4.1: Increaser & Chimney Size
Boiler
Size
Increaser Size
Vent Size
Diameter
Chimney
Height
70
105
140
165
3" to 4" (7.6 to 10.2 cm)
3" to 5" (7.6 to 12.7 cm)
3" to 5" (7.6 to 12.7 cm)
3" to 5" (7.6 to 12.7 cm)
4" (10.2 cm)
5" (12.7 cm)
5" (12.7 cm)
5" (12.7 cm)
15' (4.5 m)
15' (4.5 m)
15' (4.5 m)
15' (4.5 m)
All joints of positive pressure vent systems must be
sealed completely to prevent leakage of flue products
into the living space.
WARNING
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.
NOTICE
