Allied Air A80UH1E Installation Instructions Manual page 17

Capacity of Type B Double Wall Vents with Type B Double Wall Connectors
Serving a Single Category I Appliance
NOTE: Single appliance venting configureations with zero lateral lengths are assumed to have no elbows in the vent system. For all other vent
configurations, the vent system is assumed to have two 90 ° elbows. For each additional 90° elbow or equivalent (for example two 45° elbows equal
one 90° elbow) beyond two, the maximum capacity listed in the venting table should be reduced by 10 percent (0.90 x maximum listed capacity).
Table 3
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