Venting and Combustion Air Guide
07/21/11 AERCO International, Inc.
•
100 Oritani Dr.
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Blauvelt, NY 10913
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Ph: 800-526-0288 Page
171
of
200
GF-5050
TAG-0043_0C
The maximum pressure drop of the combustion air piping is also 140 equivalent feet (42.7 m). See
Section 3.4. 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 (42.7m), even if the combustion air is less than 140 equivalent feet, and vice versa.
Example:
The vent system of two INN800 (2 x 800,000 BTU/hr = 1,600,000 BTU/hr) consists of 30 foot length of
vent pipe and 2 sharp 90° elbows. A termination cap is also installed. Each individual vent connector
consists of 5 ft straight run and one WYE.
Common Vent pipe: 30 ft + (2 x 10ft) + 5 ft = 55 equivalent ft (16.7 m)
Individual vent connector: 5 ft + 5 ft = 10 equivalent ft (3.0 m)
Total Vent equivalent length: 55 ft + 10 ft = 65 (19.7 m)
60 equivalent ft is LESS than 140 equivalent feet: OK to use 8” Common vent piping and 6”
individual connectors.
Pg 19 of 22
