Smith Cast Iron Boilers GS110W - Manual (Page 12)

GS110 DIRECT VENT BOILER INSTALLATION AND OPERATION INSTRUCTIONS Page 12
VERTICAL VENT
POSITIVE PRESSURE SYSTEMS
See Figure 11. The vent materials used in vertical
positive pressure vent systems must be certified to UL
1738 for installations in the United States, ULS636 for
installations in Canada.
The maximum vent lengths are listed in Table 3.
Each 90
° elbow is equal to 5 linear feet (1.5 m) of pipe.
To maximize the performance of single wall sheet metal
vent systems locate 90
° elbows as far from the boiler
as possible and from one another. If any part of a single
wall metal vent system passes through an unheated
space it must be insulated with insulation rated for 400
°F. Structural penetrations must be made using
approved fire-stops.
The vent system must be both gas-tight and watertight.
All seams and joints in metal pipes must be joined and
sealed in accordance with the vent system
manufacturer's instructions. Vertical vent systems must
terminate as shown in Figures 6 & 11. An approved
terminal cap must be used.
VERTICAL VENT
NEGATIVE PRESSURE SYSTEMS
See Figures 4, 5 & 9. The GS110 is listed as a Category
I appliance when vented vertically into a metal chimney
system or masonry chimney sized as listed in Table 6.
WARNING: If an appliance using any type of a
mechanical draft system operating under
positive pressure is connected to a chimney
flue, never connect any other appliances to this
flue. Doing so can result in excessive levels of
carbon monoxide which can cause severe
personal injury or death!
Chimney Inspection & Sizing
A thorough inspection of the masonry chimney must be
performed to ensure that the chimney is clean, properly
constructed and properly sized. Exterior masonry
chimneys should not be used unless properly lined to
prevent condensation and draft problems. Table 6 lists
the equivalent breeching and flue sizes required for the
boiler/water heater. When more than one appliance is
connected to the same chimney flue the flue must be
large enough to safely vent the combined output of all
of the appliances.
Table 6 - Equivalent Breeching & Chimney Size
Note: These sizes are based on a 20 foot (6.1m)
chimney height.
inches (mm) inches (mm)
Boiler
Model
3 (7.6)
3 (7.6)
3 (7.6)
4 (10.2)
4 (10.2)
3 (7.6)
4 (10.2)
4 (10.2)
5 (12.7)
5 (12.7)
GS110-3
GS110-4
GS110-5
GS110-6
GS110-7
Intake Diameter Vent & Chimney Diameter