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Specifications subject to change without notice.
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) 90º long-radius elbows, (2) 45º 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
100 ft.
(30 M)
Use length of the longer of the vent
or air inlet piping system
Add equiv length of (3) 90º long-radius elbows
(use the highest number of elbows for either the
vent or inlet pipe)
3
x
3 ft
(0.9 M)
=
9 ft.
(2.7 M)
Add equiv length of (2) 45º long-radius elbows
(use the highest number of elbows for either the
vent or inlet pipe)
2
x
1.5 ft
(0.5 M)
=
3 ft.
(0.9 M)
Add equiv length of factory concentric vent term
0 ft.
Add correction for flexible vent pipe, if any
0 ft.
From Vent Manufacturer’s
instructions; zero for PVC/ABS DWV
Total Equivalent Vent Length (TEVL)
112 ft.
(34 M)
Add all of the above lines
Maximum Equivalent Vent Length (MEVL)
127 ft.
(38.7 M)
Is TEVL less than MEVL?
YES
Therefore, 2” pipe MAY be used
Example 2
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) 90º 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?
Measure the required linear length of air inlet and
vent pipe; insert the longest of the two here
100 ft.
(30 M)
Use length of the longer of the vent
or air inlet piping system
Add equiv length of (3) 90º long-radius elbows
(use the highest number of elbows for either the
vent or inlet pipe)
3
x
3 ft
(0.9 M)
=
9 ft.
(2.7 M)
From Vent Manufacturer’s instructions
Add equiv length of (2) 45º long-radius elbows
(use the highest number of elbows for either the
vent or inlet pipe)
0
x
=
0 ft.
(0 M)
From Vent Manufacturer’s instructions
Add equiv length of factory concentric vent term
9 M
x 3.3 ft/M
=
30 ft.
(9 M)
From Vent Manufacturer’s instructions
Add correction for flexible vent pipe, if any
1.8
x
20 ft
(6.1 M)
=
36 ft.
(11 M)
From Vent Manufacturer’s instructions
Total Equivalent Vent Length (TEVL)
175 ft.
(53 M)
Add all of the above lines
Maximum Equivalent Vent Length (MEVL)
127 ft.
(38.7 M)
Is TEVL less than MEVL?
NO
Therefore, 60mm pipe may NOT be
used; try 80mm
Maximum Equivalent Vent Length (MEVL)
250 ft.
(76.2 M)
Is TEVL less than MEVL?
YES
Therefore, 80mm pipe MAY be used
