Balancing The System - Aprilaire 8100 Owner's Manual

In order for the Aprilaire
perform most effectively, the volume of fresh air supplied
to the house must match the volume of stale air
exhausted. Because the duct work in the two airstreams
will most likely be different, the system must be balanced.
Balancing is accomplished by installing dampers in both
airstreams, measuring the airflow, then dampering down
the airflow in the stream with the highest flow until the
airflow in both streams is the same.
The following balancing procedure is recommended by
Research Products Corporation. Other measuring instru-
mentation may be used if it is accurate enough to balance
the airflow in the supply and exhaust streams to within
10% of each other.
EQUIPMENT AND MATERIALS NEEDED
• Two (2) Dwyer Magnahelic
Series 2000, 0-0.25 in. w.g. (or equal).
Do Not use a standard differential pressure gauge that
reads above 0.25 w.g. because the reading will not be
accurate for the airflows required by the Aprilaire Energy
Recovery Ventilator.
• Two (2) Research Products' airflow measuring devices.
Part No. 5158.
• Flexible tubing, 3 ⁄ " inside diameter.
16
• A 7/8" diameter hole is required to insert the airflow
measuring devices. Part No. 5158.
PROCEDURE FOR BALANCING AIR FLOW DELIVERY
1. Be sure that the two dampers are installed correctly
as shown in Figure 11.
2. Install the two airflow measuring devices into the
duct as shown in Figure 11 and seal with tape. Be
sure the airflow arrows are pointed in direction of
airflow. To get an accurate airflow measurement, the
devices must be in the center of a five foot minimum
straight duct section.

BALANCING THE SYSTEM

Energy Recovery Ventilator to
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Differential Pressure Gauges;
3. Set up the pressure gauges so that they are VERTICAL
and LEVEL and adjust to zero. Failure to do so will
result in inaccurate gauge readings.
4. Connect the tubing from the airflow measuring
devices to the pressure gauges as shown in Figure
11. Be sure to connect high pressure tap on the air-
flow measuring device to the high pressure tap on
the pressure gauge. Likewise, connect low to low
pressure taps.
5. Make sure that the two dampers are in the full open
position.
6. If the unit is connected to a forced air system, be sure
that the furnace blower is OFF.
7. Plug in the unit.
8. Read the pressure gauges. (Gauges should read
approximately 0.065 in. w.c. when air flow is at 120
cfm in the system.) If the actual gauge readings are
the same, the unit is in balance and does not
require further adjustment. Skip Step 9 and proceed
to Step 10.
9. If the gauge readings are different, slowly close the
damper on the duct with the higher gauge reading
until the two readings are identical. The unit is now
in balance.
NOTE: The other damper should remain full open.
10. Secure the dampers to prevent the set positions
from changing.
11. Disconnect tubing and pressure gauges and remove
airflow measuring devices. Seal the duct openings
where the airflow measuring devices were located.
NOTE: Be sure the damper positions have not been affected.
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