Bosch 940 ES Installation Manual page 11

Company
Z-flex
ProTech Industries
Heat-Fab
Table 5 Vent manufacturers
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.
Venting Maximum
allowable
Exhaust
pipe length
3"
28.5 ft
4"
61.25 ft
Table 6 Maximum Allowable Exhaust and Combustion
Air Lengths
6 720 644 930
Contact info
www.z-flex.com
800-654-5600
www.protechinfo.com
800-766-3473
www.heatfab.com
800-772-0739
Maximum Elbow
allowable Equivalency
Combustio
n air pipe
90° 45°
length
28.5 ft 2.5 ft 1.25 ft
61.25 ft 1.25 ft .75 ft
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 combus-
tion air piping:
90° elbows
Max number of elbows
Table 7
Two 45° elbows are equal to one 90°
i
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 7 above.
Installation instructions
3" 4"
Venting Venting
5 7
11