CleaverBrooks CFC-500 Operation, Service And Parts Manual page 14

Section 1 — Introduction
Figure 1-11 Outlet Temperature Sensor, Top of Pressure Vessel
Figure 1-12 Stack Right Side
(viewed from rear)
1-8
The stack can be mounted on the right (Figure 1-12) or left side on
the back of the boiler base.
The flue gas duct sizes may be reduced at the vent connection.
See also Chapter 4 - Stack and Intake Vent Sizing and Installation.
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Part No. 750-263