AHRI K2WT, Installation, Operating And Service Instructions

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4. Minimum Vent and Air Intake Lengths - Observe the minimum vent lengths shown in Tables 7.1, 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 below)
• 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.
Les chaudières de catégories I, II et IV doivent présenter des tronçons horizontaux dont la pente montante est d’au moins
5/8 po par pied (52 mm/m) entre la chaudière et l’évent.
Vii. Venting
A. Vent System Design (continued)
Table 7.1: Vent/ Air Intake Fitting Equivalent Length
CPVC/PVC Fitting Equivalent Length (ft)
PolyPro, Polyflue or InnoFlue
Vent Fitting
Equivalent Length (ft)
2” 90° Elbow (“Sanitary Bend”) 2.6 2” 90° Elbow 4.5
3” 90° Elbow (“Sanitary Bend”) 4.0 3” 90° Elbow 8.7
2” 90° Elbow (“Short Bend” ) 6.0 2” 90° Elbow 2.5
3” 90° Elbow (“Short Bend”) 10.0 3” 45° Elbow 4.6
2” 45° Elbow 1.5
3” 45° Elbow 2.0
2” Coupling 0.0
3” Coupling 0.0
Figure 7.2: CPVC and PVC Elbows