aldes H/E95 - Sample Door-Port Balancing Example; In-Duct Balancing Method

Residential HRV/ERV
35
Sample Door-Port Balancing Example
The static pressure reading across the fresh air is 0.19 in. w.g., indicating an airow of 187
CFM. The reading for the stale air is 0.14 in. w.g., indicating the exhaust airow is 170 CFM.
The supply airow should be adjusted to about 170 CFM (see section “Balancing Airow and
Adjusting Motor Speed” on page 32) until the pressure reading is about 0.17 in. w.g.
Example 1: Balancing using the provided airow chart
In-Duct Balancing
In-Duct Balancing consists of finding the average velocity in the duct, then multiplying
by the area to obtain airflow.
Applicable models: You would use this method with higher eciency lters.
There are three in-duct balancing methods:
1. Pitot tube and manometer or digital differential pressure gauge to measure the
velocity.
Note: Pitot tubes are not recommended for velocities below 400 FPM.
2. Airflow station or probe in the supply and exhaust ducts to measure the average
pressure, then use a conversion chart (provided by the flow station manufacturer)
to convert to velocity then to airflow. Aldes supplies an Airflow Balancing Kit (sold
separately).
Note: Compared to a pitot tube measurement, the airflow station or airflow probes
provide a higher pressure reading, making it possible to read very low airflows.
To get the most accurate results, select a differential pressure gauge that will give