Room Air Combustion; Sealed Combustion - Watts AERCO EXT Installation, Operation & Maintenance Manual

Modulex EXT Commercial Series
CHAPTER 4: Installation Instructions
Note the following:
•
Make sure that intake and exhaust openings are sufficiently sized and no reduction or closure of any
openings takes place.
•
When a combustion air or ventilation problem is not resolved, do not operate the boiler.
When contaminated combustion air is expected (near swimming pools, chemical cleaning operations,
hair salons, etc.), sealed combustion operation is recommended.
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.
C A U T I O N !
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.
OMM-0160_A • DRAFT Technical Support • (800) 526-0288 • Mon-Fri, 8 am - 5 pm EST
Page 41 of 117