Flue Gas / Exhaust Venting; Category Ii Or Iv Venting Installation - Patterson-Kelley P-K MACH CM300 Installation & Owner's Manual

3.5 Flue Gas / Exhaust Venting

All vent installations shall be in accordance with NFPA 54/ANSI Z223.1, the National Fuel Gas Code, or
CAN/ CSA-B149.1, the Natural Gas and Propane Installation Code, or applicable provisions of the local
building codes.
The vent material to be used for US and Canada is listed in the Table of Acceptable Materials for
Venting Systems located in 2.5.4.
For interior clearance requirements, refer to Sections
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. Additionally the boiler vent shall terminate at least three (3) ft. above a forced
air inlet located within ten (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. Patterson-Kelley cannot be
responsible for the effects such adverse conditions may have on the operation of the boilers.
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 with an elbow or vent tee. Similarly, a bird screen with 1"
x 1" openings is recommended for termination. Patterson-Kelley does not recommend using a vent rain
cap of any type.

3.5.1 Category II or IV Venting Installation

®
P-K MACH boilers are dual certified as Category II or IV appliances, as defined in ANSI Z21.13/CSA
4.9, latest edition and are not suit able for use with Type "B" Vents.
and Canada is listed in the Table of Acceptable Materials for Venting Systems located in 2.5.4.
Vent installations shall be in accordance with NFPA 54/ANSI Z223.1, the National Fuel Gas Code, or
CAN/ CSA-B149.1, the Natural Gas and Propane Installation Code, or applicable provisions of the local
building codes.
N : For Category II installations, ensure the flue venting system is designed to maintain a
OTE
slightly negative exhaust pressure between -0.01" W.C. and -0.05" W.C.
N : For Category IV installations, ensure the flue venting system is designed to maintain a
OTE
slightly positive exhaust pressure which MUST BE in the following ranges:
•
+0.01" W.C. and +0.22" W.C. (Direct Vent / Sealed Combustion)
•
+0.01" W.C. and +0.4" W.C. (Exhaust Only)
Revised: January 3, 2020
Released: January 3, 2020
2.4.2
 Patterson-Kelley 2020
All Rights Reserved.
P-K MACH
Technical Service 1.877.728.5351
& 2.4.3 & 2.5.5. The vent shall extend at
The vent material to be used for US
1004905980 P-K MACH CM300-CM500&C750-C1050
Installation and Owners Manual (Rev F Jan-2020).docx
®
Gas Fired Boiler
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