Harsco Industrial C1500H Installation & Owner's Manual page 26

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MACH Gas Fired Boiler
3.5.3.4 Vent Terminations
The vent shall extend at least three (3) feet above the roof, or at least two (2) feet above the highest part of any
structure within ten (10) feet of the vent. This is illustrated in the following diagram.
Additionally the boiler vent shall terminate at least 3 ft above a forced air inlet located within 10 ft.
To prevent the possible re-circulation of flue gases, the vent designer must take into consideration such things as
prevailing winds, eddy zones, building configurations, etc. Harsco Industrial, Patterson-Kelley cannot be responsible
for the effects such adverse conditions may have on the operation of the boilers. Dimensions listed above are
minimums and may not be sufficient for conditions at a specific job site.
Vertical vents are allowed to be terminated with a variety of ends, including plain straight pipe, elbow or vent tee.
Horizontal vents must be terminated as illustrated in section 3.5.5. A bird screen with 1" x 1" openings is
recommended for the termination. Harsco Industrial, Patterson-Kelley does not recommend using a vent rain cap of
any type.
3.5.4 Venting for Multiple Boilers
While the vent design parameters outlined in Section 3.5.3 still apply, achieving those same parameters in a
combined vent system, adds a significant degree of complexity. Therefore, venting systems for multiple boilers shall
be designed by experienced and knowledgeable venting professionals. The venting system shall be designed to
prevent backflow of exhaust gas through idle boilers. It is also recommended that combined venting designs be
limited to no more than four (4) boilers per combined breeching.
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