Example 1
A direct-vent 60,000 BTUH furnace installed at 2100 ft. (640M). Venting system includes FOR EACH PIPE 100 feet (30 M) of vent
pipe, 95 feet (28 M) of combustion air inlet pipe, (3) 90°-long-radius elbows, (2) 450-long-radius elbows, and a factory accessory
concentric vent kit.
Can this application use 2-in. (50 mm ND) PVC/ABS DWV vent piping?
Measure the required linear length of air inlet
and vent pipe; insert the longest of the two here
Add equiv length of (3) 900-long-radius elbows
3ff
(use the highest number of elbows for either the 3 x
vent or inlet pipe) (0.9 M)
Add equiv length of (2) 450-long-radius elbows
1.5ft
(use the highest number of elbows for either the 2 x
vent or inlet pipe) (0.5 M)
Add equiv length of factory concentric vent term
Add correction for flexible vent pipe, if any
Total Equivalent Vent Length (TEVL)
Maximum Equivalent Vent Length (MEVL)
Is TEVL less than MEVL?
Example 2
100 ft.
(30 M)
9ft.
(2.7 M)
3ft.
(0.9 M)
Oft.
Oft.
112 ft.
(34 M)
127 ft.
(38.7 M)
YES
Use length of the longer of the vent
or air inlet piping system
From Table 15
From Table 15
From Table 15
From Vent Manufacturer's
instructions; zero for PVC/ABS DWV
Add all of the above lines
For 2" pipe from Table 14
Therefore, 2" pipe MAY be used
A direct-vent 60,000 BTUH furnace installed at 2100 ft. (640M). Venting system includes FOR EACH PIPE 100 feet (30 M) of vent
pipe, 95 feet (28 M) of combustion air inlet pipe, (3) 900-long-radius elbows, and a polypropylene concentric vent kit. Also includes 20
feet (6.1 M) of flexible polypropylene vent pipe, included within the 100 feet (30 M) of vent pipe.
Assume that one meter of flexible 60mm or 80mm polypropylene pipe equals 1.8 meters of PVC/ABS pipe. VERIFY FROM VENT
MANUFACTURER'S INSTRUCTIONS.
Can this application use 60mm (o.d.) polypropylene vent piping? If not, what size piping can be used?
100 ft. Use length of the longer of the vent
(30 M) or air inlet piping system
Measure the required linear length of air inlet and
vent pipe; insert the longest of the two here
Add equiv length of (3) 900-long-radius elbows
(use the highest number of elbows for either the
vent or inlet pipe)
Add equiv length of (2) 450-long-radius elbows
(use the highest number of elbows for either the
vent or inlet pipe)
Add equiv length of factory concentric vent term
Add correction for flexible vent pipe, if any
Total Equivalent Vent Length (TEVL)
Maximum Equivalent Vent Length (MEVL)
Is TEVL less than MEVL?
3 x
0 x
3ft. 9ft.
(0.9 M) (2.7 M)
9 M x 3.3 ft/M
20 ft.
1.8 x
(6.1 M)
Maximum Equivalent Vent Length (MEVL)
Is TEVL less than MEVL?
Oft.
(0 M)
30 ft.
(9 M)
36 ft.
(11 M)
175 ft.
(53 M)
127 ft.
(38.7 M)
NO
250 ft.
(76.2 M)
YES
From Vent Manufacturer's instructions
From Vent Manufacturer's instructions
From Vent Manufacturer's instructions
From Vent Manufacturer's instructions
Add all of the above lines
For 2" pipe from Table 14
Therefore, 60ram pipe may NOT be
used; try 80ram
For 3" pipe from Table 14
Therefore, 80ram pipe MAY be used
440 01 4001 08 Specifications subject to change without notice. 55
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