Vent Piping Size - Watts Aerco Modulex EXT Series Technical Application Manual

Modulex EXT Vent and Combustion Air Application Guide

3.4. VENT PIPING SIZE

The maximum length is the combined length of straight horizontal and vertical runs, and the
equivalent straight length of fittings. The required lengths for each boiler are as shown on Table 5 and
11.
TABLE 5: Venting Pipe Run Lengths
VENT
MODEL NO.
PIPE
DIAM
ETER
4"
EXT 321
(102
EXT 481/450
mm)
EXT 641/600
6"
EXT 802/800
(152
EXT 962
mm)
EXT 1123/1100
10"
EXT 1530/1500
(254
EXT 1912
mm)
EXT 2295/2300 12"
EXT 2677/2600 (305
EXT 3060/3000 mm)
The maximum pressure drop of the combustion air piping is also 100 equivalent feet (30.5 m). See
Section 2.2. Note that this does NOT mean the allowed combined pressure drop between the vent
and combustion air is 200 equivalent feet (61 m). That is, the vent cannot go above 100 equivalent
feet (30.5 m), even if the combustion air is less than 100 equivalent feet, and vice versa.
EXAMPLES:
1. A 40 foot (12.2 m) length of vent pipe and 1 sharp 90° elbow plus a termination vent cap (rain cap)
add up to 40 ft. + 10 ft. + 10 ft. = 60 equivalent ft. (18.3 m).
2. A 30 foot (10.4 m) length of vent pipe and 2 sharp 90° elbows plus a termination rain add up to 30
ft. + (2 x 10 ft.) + 10 ft. = 50 equivalent ft. (18.3 m).
TAG-0054_0F
GF-136–V
EQUIVALENT VENT LENGTH EXAMPLES
Sharp 90° Sweep 90°
Elbow Elbow
Equiv. Ft. Equiv. Ft.
(m) (m)
10 ft. 5 ft.
(3.05 m) (1.5 m)
10 ft.
N/A
(3.05 m)
10 ft.
N/A
(3.05 m)
10 ft.
N/A
(3.05 m)
AERCO International, Inc. • 100 Oritani Dr. • Blauvelt, NY 10913
Phone: 800-526-0288
Termination
45° Elbow
Tee;
Equiv. Ft.
Equiv. Ft.
(m)
(m)
5 ft. 5 ft.
(1.5 m) (1.5 m)
5 ft. 5 ft.
(1.5 m) (1.5 m)
5 ft.
TBD
(1.5 m)
5 ft.
TBD
(1.5 m)
MAXIMUM
LENGTH
EQUIV. FT
(M)
100 ft.
(30.5 m)
100 ft.
(30.5 m)
100 ft.
(30.5 m)
100 ft.
(30.5 m)
Page 25 of 28
09/25/2017