New Buck Corporation 21 User Manual

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Floor Protection: 
Floor protection must be 3/8” minimum thickness non-combustible material or equivalent. 
 
How to use alternate materials and how to calculate equivalent thickness.        
 
An easy means of determining if a proposed alternate floor protector meets requirements listed 
in the appliance manual is to follow this procedure:               
 
1.  Convert specification to R-value: 
                    R-value is given—no conversion is needed. 
                    K– factor is given with a required thickness (T) in inches: 
                    C-factor is given: R=1/C 
2.  Determine the R-value of the proposed alternate floor protector.  
                    Use the formula in step (1) to convert values not expressed as “R” 
                    For multiple layers, add R-values of each layer to determine the overall R-value. 
3.  If the overall R-value of the system is grater than  the R-value of the specified floor protec-
tor, the alternate is acceptable. 
Example: 
The specified floor protector should be 3/4” thick material with a K-factor of 0.84. 
The proposed alternate is 4” brick  with a C-factor of 1.25 over 1/8” mineral board with a  
K-factor of 0.29.   
 
Step (a):  Use formula above to convert specification to R-value. R= 1/K x T = 1/0.84 x .75 =  
                0.893  
  Step (b):  Calculate R of proposed system.  4” brick of C=1.25, therefore Rbrick = 1/C = 
1/1.25   
                =0.80 1/8” mineral board of K = 0.29, therefore Rmin.bd. =1/029 x0.125 = 0.431             
 
Step (c):   Compare proposed system  R of 1.231 to specified R of 0.893. Since proposed  
                 system R is greater than required , the system is acceptable. 
 
Definitions: 
                  Thermal conductance   = C =         Btu      =       W 
                                                                   (hr)(ft²)(°F)    (m²)(°K)  
 
                  Thermal conductance   = K =  (Btu)(inch) =     W     =       (Btu) 
                                                                   (hr)(ft²)(°f)    (m)(°K)     (hr)(tf)(°F) 
 
                  Thermal conductance   = R  =  (ft²)(hr)(°F) = (m²)(°K) 
                                                                         Btu                W 
 
Install in accordance with 24 CFR, Part 3280 (HUD).
 
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