Figure 2: Boiler Foundation
WARNING
Failure to supply adequate air to the boiler will result in unsafe boiler operation.
C. PROVIDE AIR SUPPLY AND VENTILATION to accommodate proper combustion.
For commercial and industrial equipment, permanent facilities for supplying an ample amount of outside air shall be provided in accordance with the following.
For boiler rooms adjacent to outside walls, and where combustion air is provided by natural ventilation from the outside, there shall be a permanent air supply inlet having a total free area of not less than 1 sq. inch per 4,000 Btu per hr. (35 sq. inch per gallon per hour)
(5.5 cm2 per kw.) of total input rating of the burner or burners and in no case less than 35 sq. inch (0.425m2).
For boiler rooms not adjacent to outside walls, the combustion air shall be supplied in a manner acceptable to the authority having jurisdiction.
1.In the absence of local requirements, the confined space shall be provided with two permanent openings, one in or near the top of the room and one near the bottom. The openings shall communicate by means of ducts, with the outdoors or to such spaces (crawl or attic) that communicate with the outdoors.
a.Where communicating by means of vertical ducts, each opening shall have a free area of not less than 1 sq. inch per 4,000 Btuh (35 sq. inch per gph) (5.5 cm2 per kw) of total input rating of all appliances in the enclosure.
b.If horizontal ducts are used, each opening shall have a free area of not less than 1 sq. inch per 2,000 Btuh (70 sq. inch per gph.) (11 cm2 per kw) of total input of all appliances in the enclosure.
D. CHIMNEY OR VENT
The Series 24 boiler is designed for forced draft firing and may be used with a conventional natural draft stack (15’ minimum height) or a stub vent, sometimes called a diesel stack (see Figure 3a). See Table I for the proper vent outlet size. For low silhouette vent terminations, see Figure 3b. Draft controls are not normally required, although they may be used on installations where a natural draft stack is used or on multiple boiler installations with a common stack. The boiler is provided with a breeching damper, which should be adjusted to maintain a positive pressure of 0.1” W.C. in the vent connector box during burner high fire operation (see breeching pressure sensing port in Figure 1).
Figure 3a: Typical Arrangement for Stub Vent
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