Venting System Length Calculations - Carrier 59SC2C Series Installation, Start-Up, Operating And Service And Maintenance Instructions

Venting System Length Calculations

The Total Equivalent Vent Length (TEVL) for EACH combustion air or vent pipe equals the length of the venting system, plus the equivalent
length of elbows used in the venting system from Table 17.
Standard vent terminations or factory accessory concentric vent terminations count for zero deduction.
See vent system manufacturer's data for equivalent lengths of flexible vent pipe or other termination systems. DO NOT ASSUME that one
foot of flexible vent pipe equals one foot of straight PVC/ABS DWV vent pipe.
Compare the Total Equivalent Vent Length to the Maximum Equivalent Vent Lengths in Table 16.
Example 1
A direct- -vent 60,000 Btuh furnace installed at 2100 ft. (640 M). 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) 45_ 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 vent termination
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. (640 M) 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, and a polypropylene concentric vent kit. Also includes 20 feet (6 M)
of flexible polypropylene vent pipe, included within the 100 feet (30 M) of vent pipe.
Assume that one meter of flexible 60 mm or 80 mm polypropylene pipe equals 2 Meters of PVC/ABS pipe. VERIFY FROM VENT
MANUFACTURER'S INSTRUCTIONS.
Can this application use 60 mm (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 vent termination
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?
NOTES:
1. Use only the smallest diameter pipe possible for venting. Over ---sizing may cause flame disturbance or excessive vent terminal icing or freeze ---up.
2. NA --- Not allowed. Pressure switch will not close, or flame disturbance may result.
3. Total equivalent vent lengths under 10' for 40,000 BTUH furnaces from 0 to 2000 ft. (0 to 610 M) above sea level require use of an outlet choke plate .
Failure to use an outlet choke when required may result in flame disturbance or flame sense lockout.
4. Not all furnace families include 140,000 BTUH input models.
5. Vent sizing for Canadian installations over 4500 ft (1370 M) above sea level are subject to acceptance by local authorities having jurisdiction.
6. Size both the combustion air and vent pipe independently, then use the larger size for both pipes.
7. Assume the two 45_ elbows equal one 90_ elbow. Wide radius elbows are desirable and may be required in some cases.
8. Elbow and pipe sections within the furnace casing and at the vent termination should not be included in vent length or elbow count.
9. The minimum pipe length is 5 ft. (2 M) linear feet (meters) for all applications.
10. Use 3 ---in. (76 mm) diameter vent termination kit for installations requiring 4 ---in. (102 mm) diameter pipe.
100 ft
3 x 3 ft = 9 ft.
2 x 1.5 ft = 3 ft.
0 ft.
0 ft.
112 ft.
127 ft.
YES
100 ft
3 x 3 ft = 9 ft.
0 x = 0 ft.
9 M x 3 ft/M = 18 ft.
1.8 x 20 ft = 36 ft.
163 ft.
127 ft.
NO
250 ft.
YES
52
Use length of the longer of the vent
or air inlet piping system
From Table 17
From Table 17
From Table 17
From Vent Manufacturer's instructions;
zero for PVC/ABS DWV
Add all of the above lines
For 2" pipe from Table 16
Therefore, 2" pipe may be used
Use length of the longer of the vent
or air inlet piping system
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 16
Therefore, 60mm pipe may NOT be used;
try 80 mm
For 3" pipe from Table 16
Therefore, 80 mm pipe may be used