Multiple Boiler Venting Installation - Dunkirk DKVLT-050 Installation, Operation & Maintenance Manual

6.8 Multiple Boiler Venting Installation

• Multiple boiler application boiler can vent individually
or use common vent pipes.
• If boilers vent individually follow guidelines as
described in fi gures 6-1 through 6-7.
• If boilers vent through common vent pipes, as shown
in Figure 6-17, choose common vent pipe per Table 8.
Choose size from Table 9 for pipes between boiler and
common vent pipes.
• Longest individual vent lengths and common vent
length together must be shorter than 100 ft. (30m).
H + L ≤ 100 ft (30m) (See fi gure 6-17)
• Each boiler must have air fl ow check valve to prevent
fl ue gas back fl ow.
• External terminals follow same rule as single boiler
venting as described in Section 6.6 and 6.7
FIGURE 6-17 Mulitple Boilers With Common Venting Pipe
H
6 - COMBUSTION AIR AND VENT PIPING
Air Flow
Check Valve
Table 8 - Minimum Diameter for Individual
Boiler in Common Venting System
Table 9 - Common Venting Pipe Diameters
Total
Firing
Rate
400
600
800
1000
1200
1400
1600
1800
2000
L
Air Flow
Check Valve
30
Minimum
Model
Diameter
050 2" (51mm)
075 3" (73mm)
100 3" (73mm)
150 3" (73mm)
200 3" (73mm)
299 3" (73mm)
Minimum
Diameter of
Common vent
pipes if
L< 50 ft (16m)
4" (101mm)
5" (127mm)
6" (152mm)
7" (177mm)
Air Flow
Check Valve
Minimum
Diameter of
Common vent
pipes if
L>50 ft (16m)
5" (127mm)
6" (152mm)
7" (177mm)
8" (203mm)
Vent
Combustion
Air
12" (305mm)
Anticipated
Snow Line
Ground Level