International comfort products B Series Installation Instructions Manual page 54

INSTALLATION INSTRUCTIONS
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
Add equiv length of (3) 90º long-radius elbows
(use the highest number of elbows for either the
vent or inlet pipe)
Add equiv length of (2) 45º 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?
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
Add equiv length of (3) 90º long-radius elbows
(use the highest number of elbows for either the
vent or inlet pipe)
Add equiv length of (2) 45º 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?
Maximum Equivalent Vent Length (MEVL)
Is TEVL less than MEVL?
54
3 ft
3 x =
(0.9 M)
1.5 ft
2 x =
(0.5 M)
3 ft
3 x
(0.9 M)
0 x
9 M x 3.3 ft/M
20 ft
1.8 x
(6.1 M)
Specifications subject to change without notice.
Gas Furnace: N9MSB
100 ft Use length of the longer of the vent
(30 M) or air inlet piping system
9 ft.
From Table 15
(2.7 M)
3 ft
From Table 15
(0.9 M)
0 ft. From Table 15
From Vent Manufacturer's
0 ft.
instructions; zero for PVC/ABS DWV
112 ft.
Add all of the above lines
(34 M)
127 ft.
For 2" pipe from Table 14
(38.7 M)
YES Therefore, 2" pipe MAY be used
100 ft Use length of the longer of the vent
(30 M) or air inlet piping system
9 ft.
= From Vent Manufacturer's instructions
(2.7 M)
0 ft.
= From Vent Manufacturer's instructions
(0 M)
30 ft.
= From Vent Manufacturer's instructions
(9 M)
36 ft.
= From Vent Manufacturer's instructions
(11 M)
175 ft
Add all of the above lines
(53 M)
127 ft.
For 2" pipe from Table 14
(38.7 M)
Therefore, 60mm pipe may NOT be
NO
used; try 80mm
250 ft.
For 3" pipe from Table 14
(76.2 M)
YES Therefore, 80mm pipe MAY be used
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