Installation instructions
830 ES – 6 720 644 936 (2021/08)
18
Table 8 Vent manufacturers
Vent termination
The vent for this appliance shall not terminate:
• over public walkways; or
• near soffit vents or crawl space vents or other areas where
condensate or vapor could create a nuisance or hazard or
cause property damage; or
• where condensate vapor could cause damage or could be
detrimental to the operation of regulators, relief valves, or
other equipment.
Condensate drain requirements
An external condensate drain (not supplied with the heater)
must be installed under the following conditions:
• All vertical terminating vent installations.
• Horizontal terminating vent installations where the total
linear vent length is greater than 10 feet (3.1 m) for 3" and
5 feet (1.5 m) for 4".
• Vent installations where any section of the exhaust vent
pipe passes through an unconditioned space.
Twin pipe termination clearances
The minimum clearance between exhaust vent and combustion
air inlet terminations for twin pipe penetration is 3 feet.
Minimum combustion air and exhaust pipe length
The minimum exhaust pipe length is 1 foot (0.3m) of straight
vent pipe. The minimum combustion air pipe length is one 90°
elbow.
Maximum combustion air and exhaust pipe length
The following tables display the maximum allowable straight
pipe lengths for combustion air and exhaust piping with
consideration to the number of elbows used. Reduce the
equivalent length for each elbow used from the maximum
allowable length depending on the system used.
Table 9 Maximum Allowable Exhaust and Combustion Air
Lengths
Use of elbows
It is recommended to limit the amount of elbows used in the
exhaust and combustion air piping to reduce friction in the air
flow. The following lists the maximum amount of 90° elbows
allowed in either the exhaust or combustion air piping:
Table 10
Two 45° elbows are equal to one 90° elbow. Any
combination of 45° and 90° elbows may be used in the vent
system as long as the combination does not exceed the
maximum listed in table 9 above.
Calculation example for 3" venting:
Exhaust
Table 11
Table 12
Company Contact info
Z-flex www.z-flex.com
800-654-5600
ProTech Industries www.protechinfo.com
800-766-3473
Heat-Fab www.heatfab.com
800-772-0739
Venting Maximum
allowable
Exhaust pipe
length
Maximum
allowable
Combustion air
pipe length
Elbow
Equivalency
90° 45°
3" 28,5 ft 28,5 ft 2,5 ft 1,25 ft
4" 61,25 ft 61,25 ft 1,25 ft 0,75 ft
Max. number of 90° elbows 3" venting 4" venting
Max number of elbows 5 7
System used Concentric
Number of 90° elbows needed: 1
Number of 45° elbows needed: 2
Calculation of example
Max. length 28,5’
90° elbow reduction - 2,5’
sub-total = 26’
45° elbow reduction - 2,5’
Total = 23,5’
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