Venting System Length Calculations
The maximum length for each vent pipe (inlet or exhaust) equals the Maximum Equivalent Vent Length (MEVL) from Table 13 or Table 15
minus the number of elbows multiplied by the deduction for each elbow in Table 14.
Standard vent terminations and concentric vent terminations count for zero deductions.
See Vent Manufacturers' data for equivalent lengths of flexible vent piping.
DO NOT ASSUME that one foot of flexible vent pipe is equivalent to one foot of standard PVC vent pipe.
Example
A direct-vent 60,000 Btuh furnace installed at 2100 ft. (640 M) with 2-in.(51 mm) vent piping. Venting system includes, FOR EACH
PIPE, (3) 90 ° long radius elbows, (2) 45 ° long radius elbows and a concentric vent kit.
Maximum Equivalent Vent Length
Deduct (3) 90 long radius
Deduct (2) 45 long radius
No deduction for Concentric Vent Kit
Maximum Vent Length
3
2
X
X
= 127 ft.
3ft. = -9ft.
1.5 ft. = -3ft.
Oft. = -Oft.
= 115 ft.
(From Table 13)
(From Table 14)
(From Table 14)
(From Table 14)
For EACH vent or inlet pipe
48
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