Bosch 520PN Applications Manual page 55

4.3.2 Vent specifications
Establish vent clearances that comply with the vent manufacturer's
specifications and all applicable national/local codes.
Venting specifications
Diam. Approved terminals
E 3 or 4 inches "T" terminal
x
90° elbow
h
PVC Flue Cap*(ECAP321)Vertical terminations
a
only 3" diameter only
u
Concentric (196016)
s
t
I 3 or 4 inches "T" terminal
n
90° elbow
t
PVC Flue Cap*(ECAP321)Vertical & horizontal
a
terminations approved 3" diameter only
k
Concentric (196016)
e
Table 7 Venting specifications for intake and exhaust
[*] ULC S636-95, UL1738 certified
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 6 feet (1.8 m).
• Vent installations where any section of the exhaust vent pipe passes
through an unconditioned space.
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. Refer to table 8 if using 3" diameter venting. Refer to table 9 if
using 4" diameter venting.
Maximum
3" Venting allowable
Exhaust pipe
length
Twin pipe 31ft
system
Concentric 23ft
system
Table 8 Maximum Allowable Exhaust and Combustion Air Lengths for 3"
venting
Maximum
4" Venting allowable
Exhaust pipe
length
Twin pipe 63ft
system
Concentric 43ft
system
Table 9 Maximum Allowable Exhaust and Combustion Air Lengths for 4"
venting
C 1210 ES/ESC
Elbow
Equivalency
Combustion air
pipe length 90° 45°
31ft 5 ft 3 ft
23ft 5 ft 3 ft
Elbow
Equivalency
Combustion air
pipe length 90° 45°
63ft 2.5ft 1.5ft
43ft 2.5ft 1.5ft
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:
Max. number of 90° elbows
Twin pipe system
Concentric system
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 10 above.
Calculation example for 3" venting:
Exhaust
System used
Number of 90° elbows needed:
Number of 45° elbows needed:
Table 11
Calculation of example
Max. length
90° elbow reduction
sub-total =
45° elbow reduction
Total =
Table 12
For this example, the maximum allowable exhaust pipe
length is 12 feet.
Combustion air
System used
Number of 90° elbows needed:
Number of 45° elbows needed:
Table 13
Calculation of example
Max. length
90° elbow reduction
sub-total =
45° elbow reduction
Total =
Table 14
For this example, the maximum allowable combustion
air pipe length is 10 feet.
Installation instructions | 13
3" venting 4" venting
5 7
4 7
Concentric
1
2
23'
- 5'
18'
- 6'
12'
Concentric
2
1
23'
- 10'
13'
- 3'
10'
6 720 644 887 (2013/02)