New Buck Corporation ZCBB User Manual

This section is used for residential installation or mobile home installation. 
 
UNCONFINED SPACE: 

An unconfined space has a minimum air volume of 50 cubic feet for each 1,000 BTU/Hr (4.8m

3

 per 

Kw) input rating of all appliances in the space (Cubic feet equals Length x Width x Height of space).  
Include adjoining rooms only if there are doorless passageways or ventilation grills between the 
rooms. 

 

“The National Fuel Gas Code defines a confined space as a space whose volume is less than 50 cubic 
feet per 1,000 BTU per hour (4.8m

3

 per KW) of the aggregate input rating of all appliances installed 

in that space.   
“WARNING:  If the area in which the heater may be operated is smaller than that defined as an 
unconfined space, provide adequate combustion and ventilation air by one of the methods 
described in the National Fuel Gas Code, ANSI Z223.1,  1992, Section 5.3” 

 
DETERMINE IF YOU HAVE A CONFINED OR UNCONFINED SPACE 
 
Use this worksheet to determine if you have a confined or unconfined space. 
 
SPACE:  Include the room in which you will install heater plus adjoining rooms with doorless 
passageways or ventilation grills between the rooms. 
 

1.  Determine the volume of the space (length x width x height). 
     Length x Width x Height= ________ cu.ft. (volume of space) 
     EXAMPLE: 

20 ft. (length) x 16 ft. (width) x 8 ft. (ceiling height) = 

 

 

        2560 cu. ft. (volume of space) 

 
If additional ventilation to adjoining room is supplied with grills or openings, add the volume of these 
rooms to the total volume of space. 
 

2.   Divide the space volume by 50 cubic feet to determine the maximum BTU/Hr the space 
     can support. 
    ________ (volume of space)  / 50 cu. ft = (maximum BTU/Hr the space can support) 
    EXAMPLE:  2560 cu. ft. (volume of space) / 50 cu. ft. = 51.2 or 
                         51200 (maximum BTU/Hr the space can support.) 
 

 

 

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