Sears 153.335941 For Appliances Located in Confined Spaces, ALL AIR from Inside Buildings

Installation Instructions (cont'd)

Combustion Air and Ventilation

for Appliances Located in Unconfined Spaces

Unconfined Space is a space whose volume is not less than 50 cubic feet per 1,000 Btu per hour of the aggregateinput rating of all appli- ances installed in that space. Rooms communicating directly with the space in which the appliances areinstalled, through openings not fur- nished with doors, areconsidered a part of the unconfined space.

In unconfined spaces in buildings, infiltration may be adequate to provide air for combustion, ventilation and dilution of flue gases. However, in buildings of tight construction (for example, weather stripping, heavilyinsulated, caulked, vapor barrier, etc.), additionalair may need to be provided using the methods described in Combustion Air and Ventilation for Appliances Locatedin Confined Spaces.

1.When directly communicating with the outdoors, each opening shall have a minimum free area of 1 square inch per 4,000 BTU per hour of total input rating of all equipment in the enclosure. (See Figure6.)

2.When communicating with the outdoors through vertical ducts, each opening shall have a minimum free area of I square inch per 4,000 BTU per hour of total input rating of all equipment in the enclosure. (See Figure 7.)

VENTILAT_ LO_I:_

Combustion Air and Ventilation

for Appliances Located in Confined Spaces

Confined Space is a space whose volume is less than 50 cubic feet per

1,000 Btu per hour of the aggregate input rating of all appliances installed in that space.

a. ALL AIR FROM INSIDE BUILDINGS:

(See Page 8 Figure 1, and Figure 5 below)

The confined space shall be provided with two permanent open- ings communicating directly with an additional room(s) of suffi- cient volume so that the combined volume of all spaces meets the

criteria for an unconfined space. The total input of all gas utiliza- tion equipment installed in the combined space shall be considered in making this determination. Each opening shall have a minimum free area of one square inch per 1,000 BTU per hour of the total

input rating of all gas utilization equipment in the confined space, but not less than 100 square inches. One opening shall commence

within 12 inches of the top and one commencing within 12 inches of the bottom of the enclosure.

	VENT TO
Ir_=T AIR DOfff	]O_O0_S

I Figure 7 ] ,,,,,,,,,,,,,,,,A,,,I

3.When communicating with the outdoors through horizontal ducts, each opening shall have a minimum free area of 1 square inch per 2,000 BTU per hour of total input rating of all equip- ment in the enclosure. (See Figure8.)

CEt4T TO

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I Figure 5 [

b. ALL AIR FROM OUTDOORS: (see Figures 6-8)

The confined space shall be provided with two permanent open-

ings, one commencing within 12 inches of the top and one com- mencing within 12 inches from the bottom orthe enclosure.

The openings shall communicate directly, or by ducts, with the

outdoors or spaces (crawl or attic) that freely communicate with the outdoors.

Figure 6 1

Figure 8 1

4.When ducts are used, they shall be of the same cross-sectional area

as the free area of the openings to which they connect. The mini- mum short side dimension of rectangular air ducts shall nor be less than 3 inches. (See Figure 8.)

5.Louvers and Grilles: In calculating free area, consideration shall be

given to the blocking effect of louvers, grilles or screens protect- ing openings. Screens used shall not be smaller than ¼ inch mesh.

If the free area through a design of louver or grille is known, it should be used in calculating the size opening required to provide the free area specified. If the design and free area is not known, it may be assumed that wood louvers will be 20-25 percent free area

and metal louvers and _rilles will have 60-75percent free area. Louvers and .grilles shall be fixed in the open position or inter-

locked with the equipment so that they are opened automatically during equipment operation.

6. Special Conditions Created b7 Mechanical Exhausting or Fireplaces: Operation of exhaust fans, ventilation systems, clothes

dryers or firefplaces may create conditions requiring special atten- tion to avoica unsarisfactory operation of installed gas utilization eqmpment.

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