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Example of Fresh Air Damper Sizing using the Design Method:
Step 1:
1500 sq. ft. home, 3 bedrooms, ASHRAE62.2-2010 standard. From Table
2A, continuous ventilation required is 45 CFM. For damper sizing multiply
continuous ventilation value by 3 equates to 135 CFM for fresh air damper
size.
Step 2:
Static pressure in the return is 0.15 inches WC (measured).
Step 3:
Ductwork system design consists of:
i.
ii.
iii.
Step 4:
The 6 inch Fresh Air Damper delivers 136 CFM in smooth duct at 30
equivalent feet and would be the appropriate damper for this system.
Refer to Field Controls Ventilation Reference Guide for additional information on proper sizing of Fresh
Air Damper and ductwork.
10B. HOW TO SIZE AN HRV/ERV
As a minimum, double the continuous ventilation fl ow rate for sizing the HRV/ERV product.
Use the HRV/ERV air fl ow rate as the CFM HEAT and CFM COOL dial setting on the FAVC unit.
Table 8: Fresh Air Damper Sizing Chart
Two 6" diameter 45° Elbow (10 equivalent feet),
10 feet of straight 6" smooth diameter ductwork (10 equivalent feet).
The system has 20 equivalent feet of smooth duct (10 + 10 = 20)
Page 33 of 36
P/N 780100700 07/18 Rev F
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