Room Air Combustion; Sealed Combustion - Watts AERCO Modulex EXT Commercial Series User Manual

Modulex EXT Commercial Series Boilers User Manual
CHAPTER 4: Installation Instructions
When one expects contaminated combustion air (near swimming pools, chemical cleaning
operations, hair salons, etc.), sealed combustion operation is recommended.
WARNING!
Fire danger due to flammable materials or liquids. Do not store flammable materials and
liquids in the immediate vicinity of the boiler.
CAUTION!
See Section 4.7.2 for warnings and guidelines concerning materials and contaminants that
should be avoided in the boiler room and near air inlets when operating the boiler.

4.21.2 Room Air Combustion

The boiler 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).

4.21.3 Sealed Combustion

The boiler 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.
Page 44 of 144
09/15/2017
AERCO International, Inc. • 100 Oritani Dr. • Blauvelt, NY 10913
Phone: 800-526-0288
OMM-0095_0H
GF-139