Modulex Light Commercial Series
CHAPTER 4: Installation Instructions
OMM-0158_A
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W A R N I N G !
Fire danger due to flammable materials or liquids. Do not store flammable materials and liquids
in the immediate vicinity of the boiler.
See Section 4.6.2 for warnings and guidelines concerning materials and contaminents that
should be avoided in the boiler room and near air inlets when operating the boiler.
Room Air Combustion
The boiler closet or room shall be provided with two permanent openings communicating directly
with an additional room(s). The total input of all gas utilization equipment installed in the combined
space shall be considered in making this determination. Each opening shall have a minimum free
area of 1 square inch per 1,000 Btu per hour of total input rating of all gas utilization equipment
in the confined space, but no less than 100 square inches. One opening shall commence within
12 inches (305 mm) of the top, and one opening shall commence within 12 inches (305 mm) of
the bottom of the enclosure. The minimum dimension of air openings shall not be less than 4
inches (101.6 mm).
Sealed Combustion
The boiler closet or room shall be provided with two permanent openings, one commencing within
12 inches (305 mm) from the top of the enclosure, and one commencing within 12 inches (305
mm) from the bottom of the enclosure. The openings shall communicate directly, or by ducts, with
the outdoors or spaces (crawl or attic) that freely communicate with the outdoors. The minimum
dimension of air openings shall be no less than 4 inches (101.6 mm).
1) Where directly communicating with the outdoors, each opening shall have a minimum free
area of 1 square inch per 4,000 Btu/hr of total input rating of all equipment in the enclosure.
2) Where communicating with the outdoors through vertical ducts, each opening shall have a
minimum free area of 1 square inch per 4,000 Btu/hr of total input rating of all equipment in
the enclosure.
3) Where communicating with the outdoors through horizontal ducts, each opening shall have a
minimum free area of 1 square inch per 2,000 Btu/hr of total input rating of all equipment in
the enclosure.
4) Where ducts are used, they shall be of the same cross-sectional area as the free area of the
opening to which they connect.
4.24 Installation Of The Exhaust And Air Intake System
NOTE:
Consult local and state codes pertaining to special building code and fire department
requirements. Adhere to national code requirements.
Observe the listed maximum lengths of vent system, which are dependent on boiler model. The
maximum permissible lengths are listed in section 4.25, below.
Minimum clearance of 4 ft. (1.22m) horizontally from, and in no case above or below, unless a 4
ft (1.22 m) horizontal distance is maintained, from electric meters, gas meters, regulators and
relief equipment.
The minimum distance from adjacent public walkways, adjacent buildings, openable windows and
building openings shall not be less than those values specified in the National Fuel Gas Code,
ANI Z223.1 / NFPA 54 and/or the Natural Gas and Propane Installation Code CAN/CSA B149.1.
Do not extend exposed vent pipe outside the building beyond recommended distance.
Condensate could freeze and block vent pipe.
Vent should terminate at least 3 ft (915 mm) away from adjacent walls, inside corners and 5 ft.
(1525 mm) below roof overhang (see Figure 4-27).
