Harsco Industrial MACH C1500GG Installation & Owner's Manual page 18

3.5.3.3 CATEGORY IV INSTALLATIONS
If the vent installation is designed for Category IV conditions only (condensing – positive pressure) as it is defined in
ANSI Z21.13/CSA 4.9, latest edition. The vent material must be as listed in Table in section 3.5.1.2 and can be run
horizontally or vertically.
Vent installations shall be in accordance with NFPA54/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.
(Category IV). Harmful flue gases may leak into the room which can cause serious injury or death.
3.5.3.4 Required Clearances
Provide clearances between combustion air intake, exhaust vent, roof and wall surfaces, doors and window, and
snow line. Refer to Figure below: Termination Clearances – Forced Draft and Direct Vent Installations.
Reference: NFPA 54/ANSI Z223.1 National Fuel Gas Code
of condensation can cause icing of the walking surface. Maintain a minimum clearance of 4 ft (1.22 m)
horizontally from any electric or gas meter, regulator or relief equipment.
Conventional Vent Systems Clearances
The following termination clearance requirements are for conventional, non-direct vent installations.
The vent system shall terminate at least 3 ft above a forced air inlet within 10 feet horizontally.
The vent system shall terminate at least 4 ft below, 4 ft horizontally from or 1 ft above any door, operable window
or gravity inlet into any building. The bottom of the vent terminal shall be at least 12 in. above grade or highest
expected snow line (if applicable).
Do not use a barometric damper if operating with a positive stack pressure
Do not locate intake or exhaust terminations directly above a walkway; dripping
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MACH® Gas-Fired Boiler