Common Vent Piping - 199 Model Only; Vent Diameter Sizing And Lengths - Westinghouse WGRT 150 Series Installation Start-Up Maintenance Parts

F. COMMON VENT PIPING – 199 MODEL ONLY!
DO NOT ATTEMPT to common vent 150 model water heaters. Doing so will
result in property damage, severe personal injury, or death.
Common Vented water heaters must be direct vented, with an exhaust vent and
intake air pipe vented to the outdoors. DO NOT power vent Common Vented
water heaters! Doing so will result in property damage, severe personal injury,
or death.
These units can be common vented. Connecting several units together requires
proper sizing of the intake and exhaust pipes. Up to eighteen units can be
common vented together.

1. VENT DIAMETER SIZING AND LENGTHS

These water heaters are designed for 3 inch exhaust vent and intake pipes. The
following chart outlines the maximum length of common venting allowable. A vent
system's length is calculated by adding the length of all straight pieces used (both
horizontal and vertical) and then adding the equivalent lengths of each fitting used
in the system. A vent system's length must not exceed the maximum length
outlined in the chart below.
Number of Water
Heaters Common Vented
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
Table 14 – Maximum Common Vent Length for Direct Vent (2 Pipe)
NOTE: Reduce the maximum equivalent length above by 5 feet per 90
the above set limits.
Maximum Vent Length (in Ft.) for Direct Vent (2 Pipe)
Load (BTU/Hr)
3"
199,000
100
398,000 50
597,000
796,000
995,000
1,194,000
1,393,000
1,592,000
1,791,000
1,990,000
N/A
2,189,000
2,388,000
2,587,000
2,786,000
2,985,000
3,184,000
3,383,000
3,582,000
Pipe Size
4" 6"
N/A
N/A
83
58 133
101
75
67
58
N/A
N/A
o
elbow used and by 2 feet per 45
8" 10"
N/A
N/A
117
99
89
79 124
71 110
65 101
59 92
86
79
74
N/A
70
65
62
o
elbow used. DO NOT exceed
WHL-004 REV. 5.26.17
29
12"
N/A
114
107
101
N/A