Watts Aerco Modulex EXT Series Technical Application Manual page 14

Modulex EXT Vent and Combustion Air Application Guide
EXAMPLES:
The combustion air system of two EXT 1123/1100 (2 x 1,123,000 BTU/hr. = 2,246,000 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)
95 equivalent ft. is LESS than 100 equivalent feet: OK to use 8" Common air intake piping and
6" individual connectors.
Figure 9: Typical Common Combustion Air Inlet installation Through Roof
Page 14 of 28
09/25/2017
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