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P/N 780100700 07/18 Rev F
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
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.
Two 6” diameter 45° Elbow (10 equivalent feet),
ii.
10 feet of straight 6” smooth diameter ductwork (10 equivalent feet).
iii.
The system has 20 equivalent feet of smooth duct (10 + 10 = 20)
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.
Table 8: Fresh Air Damper Sizing Chart
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.
