Bradford-White Corp B4 用户手册

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Page 6

Copper Brute B4 Volume Water Heaters

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directly, or by ducts, with the outdoors or spaces that 

freely communicate with the outdoors.  When directly 

communicating with the outdoors directly, or through 

vertical ducts, each opening shall have a minimum 

free area of 1 square inch per 4000 Btu/hr (550 square 

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

enclosure.  When communicating to the outdoors 

through horizontal ducts, each opening shall have a 

minimum free area of not less than 1 square inch per 

2000 Btu/hr (1100 square mm/kW) of total input rating 

of all equipment in the enclosure.

  One permanent opening, commencing within 

12" (30 cm) of the top of the enclosure shall be 

permitted.  The opening shall directly communicate 

with the outdoors or shall communicate through a 

vertical or horizontal duct to the outdoors or spaces 

that directly communicate with the outdoors, and shall 

have a minimum free area of 1 square inch per 3000 

Btu/hr (734 square mm/kW) of the total input rating of 

all equipment located in the enclosure.  This opening 

must not be less than the sum of the areas of all vent 

connectors in the confined space.

Other methods of introducing combustion and 

ventilation air are acceptable, providing they conform 

to the requirements in ANSI Z223.1, or applicable 

codes.

In Canada, Table 2 does not apply.  Consult 

local building and safety codes or, in absence of such 

requirements, follow CAN/CGA B149.

NOTE: Check with louver manufacturers for net 

free area of louvers. If screens or louvers are installed, 

add 50 percent for each screen/louver to the net free 

area Check all local codes applicable to combustion 

air.

When combustion air comes directly through an 

outside wall, each opening must have a minimum free 

area of at least one square inch for each 4,000 BTU/h 

input of the total input rating of all appliances in the 

enclosed area. (In Canada, refer to CGAB149.1 and .2.)

Confined and non-confined areas have different 

requirements for installation. Consult the latest edition 

of the National Gas Code for installation requirements.

Any equipment which uses air or removes air 

from the heater room can use up the combustion air 

supply or reverse the natural draft action of the venting 

system. This could cause flue products to build up in 

the heater room. More air must be supplied to make up 

for the decrease.

         175                   44           284                44           284

         250                   63           406                63           406

         325                   82           529                82           529 

         400                  100          645               100          645

  

Note:  For screens or louvers, add 50%.

1.  The drafthood must sit directly on top of the heater  

  as shown and must not be altered in any manner.

2.  An Underwriters' Laboratories listed vent cap is   re- 

  quired to eliminate downdraft and allow the heater  

  to function properly.

3.  Use approved roof fitting.

In the United States, the most common 

requirements specify that the space shall communicate 

with the outdoors in accordance with method 1 or 2, 

which follow.  Where ducts are used, they shall be of 

the same cross-sectional area as the free area of the 

openings to which they connect.

Two permanent openings, one commencing 

within 12" (30 cm) of the top and one commencing 

within 12" (30 cm) of the bottom of the enclosure 

shall be provided.  The openings shall communicate 

10 ft.

(3.0m)

2 ft. (0.6m)

Listed Vent

Cap

Storm Collar

Roof Jack

Adequate

Air Supply

To Room

Top and

Botom

1/14 in. (6mm)

Minimum Pitch

Per Foot of

Horizontal Pipe

Drafthood

12 in.

(305mm)

All Sides

Vent terminated at

least 24 in.

(610mm) above

any object within

10 ft. (3.0m)