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VII. Venting
A. Vent System Design (continued)
NOTICE Do not exceed maximum vent/combustion air system length. Refer to Tables 7.1B, 7.5, 7.13, and
7.21 in this section for maximum vent/combustion air system length.
Use Use only vent and combustion air terminals and terminal locations shown in Tables 7.1B, 7.5, 7.13 and
7.21.
4. Minimum Vent and Air Intake Lengths - Observe the minimum vent lengths shown in Tables 7.5, 7.13 and 7.21.
5. Clearances to Combustibles - Maintain the following clearances from the vent system to combustible
construction:
• Vent - 1/4" (also observe clearances through both combustible and non-combustible walls - see 9)
• Air Intake - 0"
• Concentric Portion of Concentric Terminals - 0"
6. Pitch of Horizontal Vent Piping - Pitch all horizontal vent piping so that any condensate which forms in the piping
will run towards the boiler.
• Pitch CPVC/PVC vent piping 1/4" per foot.
• Pitch Polypropylene vent piping 5/8" per foot.
For Category I, II, and IV boilers, have horizontal runs sloping upwards not less than 1/4" per foot (21 mm/m)
from the boiler to the vent terminal.
Les chaudières de catégories I, II et IV doivent présenter des tronçons horizontaux dont la pente montante est d'au
moins 1/4 po par pied (21 mm/m) entre la chaudière et l'évent.
Table 7.1B: Vent/ Air Intake Fitting Equivalent Length
CPVC/PVC Fitting
2" 90° Elbow ("Sanitary Bend")
3" 90° Elbow ("Sanitary Bend")
2" 90° Elbow ("Short Bend" )
3" 90° Elbow ("Short Bend")
2" 45° Elbow
3" 45° Elbow
2" Coupling
3" Coupling
107672-03 - 5/18
PolyPro, Polyflue
Equivalent
or InnoFlue
Length (ft)
Vent Fitting
2.6
2" 90° Elbow
4.0
3" 90° Elbow
6.0
2" 45° Elbow
10.0
3" 45° Elbow
1.5
2.0
0.0
0.0
Figure 7.2: CPVC and PVC Elbows
Equivalent
FasNSeal
Length (ft)
Vent Fitting
4.5
3" 90° Elbow
8.7
3" 45° Elbow
2.5
3" Straight Tee
4.6
3" Boot Tee
Equivalent
Length (ft)
4.0
2.0
18.0
8.0
17
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