Balancing The System - Nu-Air NU0103 Operating, Maintaining & Installing

10 Balancing the System

Once the H/ERV system is installed, do the following:
1. Close all windows and doors.
2. Turn off any exhaust only systems.
3. To balance the H/ERV, set the machine on high speed.
4. Make a small hole in the supply duct at least 2 feet down stream of the motor. Insert a
Pitot tube in the cross sectional center of the duct.
5. Measure the velocity pressure with a digital manometer or magnehelic gauge.
6. Record the value and repeat the procedure for the exhaust air stream.
7. Use the motor speed control buttons on the side of the unit to reduce airflow until the
velocity pressure equals that of the opposite air stream.
To balance the H/ERV, you will need a device to measure air flow. It is recommended to use
either a magnehelic gauge or a pitot tube air meter (discussed here). Depending on the device
you are using, follow one of the two procedures below:
Magnehelic Gauge: (Part # 2000-00 – not shown)
1. Disengage one end of the exhaust flexible duct connector in the main duct before any branch
ducts and push the duct back into itself. Insert the flow grid and tape the joint between the
flow grid and ductwork.
2. Set the HRV on high speed. Mount the magnehelic gauge level and plumb. Join the hoses
from the flow grid to the magnehelic gauge. The needle of the magnehelic gauge should read
positively. Switch hose connections if the needle falls below zero.
3. Record reading from gauge. Repeat the procedure for the supply duct.
4. Go back to the duct with the higher reading and adjust the motor speed until the supply air is
equal to the exhaust air reading.
Rev 2.3 July 17, 2017
Digital Manometer & Pitot Tube (Supplied by Others)
19