Smith Cast Iron Boilers GS110W operation manual Intake Air Option - General Guidelines

Page 6 GS110 DIRECT VENT BOILER INSTALLATION AND OPERATION INSTRUCTIONS

Figure 5 - Vertical Negative Pressure Metal Chimney System and Inside Combustion Air (Cat. I)

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.

Table 2 - Combustion Air System Sizing

Boiler	Equivalent Intake	Equivalent Intake
Model	Length (see note)	Length (see note)
Number	3” Diameter	4” Diameter
GS110-3	45 feet (13.7 m)	65 feet (19.8 m)
GS110-4	45 feet (13.7 m)	65 feet (19.8 m)
GS110-5	45 feet (13.7 m)	65 feet (19.8 m)
GS110-6	n/a	* 40 feet (12.2 m)
GS110-7	n/a	* 40 feet (12.2 m)

* 4" to 3" reducer required.

Note: Subtract 5 feet (1.5 m) for each 90° elbow.