Crown Boiler 24-07 User Manual

11

.  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 cm

2 

per kw.) of total input rating of the burner or 

burners and in no case less than 35 sq. inch (0.425m

2

).

 

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 cm

2

 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 cm

2

 

per kw) of total input of all appliances in the 

enclosure.

.  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).