Venting and Combustion Air Guide
07/21/11 AERCO International, Inc.
•
100 Oritani Dr.
•
Blauvelt, NY 10913
•
Ph: 800-526-0288 Page
163
of
200
GF-5050
TAG-0043_0C
Total BTU/hr
Input
(up to and
including)
Common
Pipe
Diameter
Equivalent Common Pipe Lengths Examples
Maximum Length
à
Individual
Connector plus
Common
Combustion Air
Equivalent Ft (m)
Sharp 90°
Elbow
Equiv. Ft
(m)
Sweep 90°
Elbow
Equiv. Ft
(m)
45° Elbow
Equiv. Ft
(m)
WYE
Equiv. Ft
(m)
1,200,000
6”
(152 mm)
10 ft.
(3.05 m)
N/A
5 ft.
(1.5 m)
5 ft.
(1.5 m)
140 ft.
(42.7 m)
2,120,000
8”
(203 mm)
10 ft.
(3.05 m)
N/A
5 ft.
(1.5 m)
5 ft.
(1.5 m)
140 ft.
(42.7 m)
3,180,000
10”
(254 mm)
10 ft.
(3.05 m)
N/A
5 ft.
(1.5 m)
5 ft.
(1.5 m)
140 ft.
(42.7 m)
4,240,000
12”
(305 mm)
10 ft.
(3.05 m)
N/A
5 ft.
(1.5 m)
5 ft.
(1.5 m)
140 ft.
(42.7 m)
NOTES:
•
The chart above shows equivalent pipe lengths of the fittings for the common combustion air
pipe. See section 2.2 for equivalent lengths for fittings for the individual unit connector.
•
The maximum equivalent length shown is the sum of the equivalent length of the longest
individual connector plus the equivalent length of the common combustion air pipe.
If the
maximum equivalent length exceeds 140 equivalent ft, contact your AERCO sales
representative or AERCO International for design assistance and approval.
•
It is important to use a WYE as a means to connect the individual combustion air pipe into the
common combustion air pipe. This will ensure the least amount of pressure drop. Do NOT use a
TEE, 90°, or 45° elbow.
The maximum pressure drop of the vent is also 140 equivalent feet (42.7 m). See Section 3.4.5. Note
that this does
NOT
mean that the allowed combined pressure drop between the vent and combustion
air is 280 equivalent feet (85.3 m). That is, the vent cannot go above 140 equivalent feet (42.7 m),
even if the combustion air is less than 140 equivalent feet, and vice versa.
Examples:
The combustion air system of two INN1060 (2 x 1,060,000 BTU/hr = 2,120,000 BTU/hr) consists of 30
foot length of common combustion air pipe and 3 sharp 90° elbows. The termination includes two (2) 90°
elbows. Each individual combustion air connector consists of 10 ft straight run and one WYE.
Common Combustion air pipe: 30 ft + (3 x 10ft) + (2 x 10ft) = 80 equivalent ft (24.3 m)
Individual combustion air connector: 10 ft + 5 ft = 15 equivalent ft (4.6 m)
Total Combustion air equivalent length: 80 ft + 15 ft = 95 (29.0 m)
135 equivalent ft is LESS than 400 equivalent feet: OK to use 8” Common air intake piping and 6”
individual connectors.
Pg 11 of 22
