Smith Cast Iron Boilers GS110W - Manual (Page 6)

GS110 DIRECT VENT BOILER INSTALLATION AND OPERATION INSTRUCTIONS Page 6
Intake Air Option - General Guidelines
This configuration provides combustion air directly to the
boiler using a dedicated pipe. Combustion air can be
drawn in horizontally through an outside wall or vertically
through the roof, see Figures 6, 7, 8, 9 & 10.
WARNING: Each boiler must have it's own intake
air system. Common intake air systems are not
to be used! Improper installation can result in
excessive levels of carbon monoxide which can
cause severe personal injury or death!
Single wall galvanized smoke pipe, single wall aluminum
pipe, flexible aluminum pipe, PVC or CPVC pipe can be
used for the intake air pipe. Maximum intake lengths
must not be exceeded per Table 2, larger diameters may
be used on 3,4,and 5 section boilers.
Figure 5 - Vertical Negative Pressure Metal Chimney System and Inside Combustion Air (Cat. I)
Equivalent Intake
Length (see note)
4” Diameter
Equivalent Intake
Length (see note)
3” Diameter
Boiler
Model
Number
65 feet (19.8 m)
65 feet (19.8 m)
65 feet (19.8 m)
* 40 feet (12.2 m)
* 40 feet (12.2 m)
45 feet (13.7 m)
45 feet (13.7 m)
45 feet (13.7 m)
n/a
n/a
GS110-3
GS110-4
GS110-5
GS110-6
GS110-7
Table 2 - Combustion Air System Sizing
* 4" to 3" reducer required.
Note: Subtract 5 feet (1.5 m) for each 90
° elbow.