Flow Collars - Bryant HRVBBLHU Installation, Start-Up, And Operating Instructions Manual

II. FLOW COLLAR
Flow Collars are temporary, and should be installed as close to
HRV as possible and in straightest sections of duct to ensure
accuracy (See Fig. 15). If only 1 flow collar is available, install
collar in stale-air duct of HRV, and record airflow. Next, install
collar in the fresh-air duct and record airflow. If 2 flow collars are
available, it will be much easier to read airflow and properly adjust
dampers to balance unit.
With speed control at maximum speed (high-speed operation) and
continuous air exchange occurring with outside, connect hoses
from flow collar to a magnehelic gage (See Fig. 17). The gage
must be leveled and zeroed before use to read accurately. If needle
falls below zero, reverse hose connections.
Measure exhaust air first, it is typically the lowest pressure due to
nature of system and ductwork. Next, measure fresh air. If fresh air
reading is higher than exhaust reading, adjust damper until reading
is same. If reading is lower, return to exhaust damper and adjust to
obtain same reading. You can use label on flow collar to convert
static pressure into airflow.
Once HRV is balanced and dampers are adjusted to equalize
airflow, use tape or drive screws to prevent damper blades from
moving. Remove flow collars and secure ducts. This procedure
should be repeated to ensure unit is balanced properly.
STALE AIR
TO OUTSIDE
6°C
43°F
FRESH AIR
TO BUILDING
16°C
61°F
Fig. 18—HRVBBLHU and HRVBBSVU
Cross Flow
STALE AIR
TO OUTSIDE
FRESH AIR
TO BUILDING
Fig. 20—HRVBBLHU Airflow During
Air Exchange
FRESH AIR
FROM OUTSIDE
0°C
32°F
STALE AIR
FROM BUILDING
22°C
72°F
A98403
FRESH AIR
FROM OUTSIDE
STALE AIR
FROM BUILDING
A99269
—11—
MAX
MIN
ZEROING SCREW
Fig. 17—Magnehelic Gage
NOTE: The flow collar directional arrow (on flow collar) must be
oriented in the airflow direction of unit.
NOTE: Some field modification may be required to ensure proper
temporary installation of flow collar during balancing when
insulated flexible duct is used.
STALE AIR
TO OUTSIDE
2°C
36°F
Fig. 19—HRVBBLVU Counterflow
FILTERED AIR
TO BUILDING
Fig. 21 —HRVBBLHU Airflow
During Defrost
MAX
MIN
AIRFLOW
DIRECTION
FLOW
COLLAR
CONVERSION
CHART
A98400
FRESH AIR
FROM OUTSIDE
0°C
32°F
STALE AIR
FROM BUILDING
22°C
72°F
FRESH AIR
TO BUILDING
20°C
68°F
A98404
STALE AIR
FROM BUILDING
A99270