Kenmore 153.33207 Benutzerhandbuch

12

Chemical vapor corrosion of the fl ue, blower assembly and vent system 
may occur if air for combustion contains certain chemical vapors.  Spray 
can propellants, cleaning solvents, refrigerator and air conditioner 
refrigerants, swimming pool chemicals, calcium and sodium chloride, 
waxes, bleach and process chemicals are typical compounds which 
are potentially corrosive.

A.  ALL AIR FROM INSIDE BUILDINGS: (See Figure 10 and 11)

The confi ned space shall be provided with two permanent openings 

communicating directly with an additional room(s) of suffi cient volume 
so that the combined volume of all spaces meets the criteria for an 
unconfi ned space.  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 one 
square inch per 1,000 Btu per hour (22 cm

2

/kW) of the total input rating of 

all gas utilization equipment in the confi ned space, but not less than 100 
square inches (645 cm

2

). One opening shall commence within 12 inches 

(31 cm) of the top and one commencing within 12 inches (31 cm) of the 
bottom of the enclosures.

                         

B. ALL AIR FROM OUTDOORS: (See Figures 12, 13 and 14)

The confi ned space shall be provided with two permanent openings, 

one commencing within 12 inches (31 cm) of the top and one
commencing within 12 inches (31 cm) 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.

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 
(5.5  cm

2

/kW) of total input rating of all equipment in the enclosure, 

see Figure 12.                                     

                                      
                                                                    FIGURE 12.

2.   When communicating with the outdoors through vertical ducts, each 

opening shall have a minimum free area of 1 square inch per 4,000 
Btu per hour (5.5 cm

2

/kW) of  total input rating of all equipment in the 

enclosure, see Figure 13.

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 (11 cm

2

/kW)) of  total input rating of all equipment 

in the enclosure, see Figure 14.

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 minimum 
short side dimension of rectangular air ducts shall not be less than 
3 inches (7.6 cm), see Figure 14.

                                                

  

5.  Alternatively a single permanent opening may be used when 

communicating directly with the outdoors, or with spaces that freely 
communicate with the outdoors. The opening shall have a minimum 
free area of 1 square inch per 3,000 BTU per hour (8.3 cm

2

/kW) of 

total input rating of all equipment in the enclosure. See Figure 14A.

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

given to the blocking effect of louvers, grilles or screens protecting 
openings. Screens used shall not be smaller than 1/4 inch 
(6.4 mm) 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 specifi ed.  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 grilles will have 60-75 percent 
free area.  Louvers and grilles shall be fi xed in the open position or 
interlocked with the equipment so that they are opened automatically 
during equipment operation.

7.   Special Conditions Created by Mechanical Exhausting or Fireplaces: 

operation of exhaust fans, ventilation systems, clothes dryers or 
fi replaces may create conditions requiring special attention to avoid 

unsatisfactory operation of installed gas utilization equipment.