Checking Supply Air CFM
To check the supply air CFM after the initial balancing has
been completed:
1.Remove the two ¼ inch dot plugs in the duct panel.
2.Insert at least 8 inches of ¼ inch tubing into each of these
holes for sufficient penetration into the airflowon both sides
of the indoor coil.
3.Using an inclined manometer, determine the pressure drop
across the dry evaporator coil. Since the moisture on an
evaporator coil may vary greatly, measuring the pressure
drop across a wet coil under field conditions would be inac-
curate. To ensure a dry coil, the compressors should be de-
activated while the test is being run.
4.Knowing the pressure drop across a dry coil, the actual
CFM through the unit can be determined from the curve in
Coil Delta P vs. Supply Air CFM figure.
WARNING!
Failure to properly adjust the total system air
quantity can result in extensive system damage.
After readings have been obtained, remove the tubes and
reinstall the two ¼ inch plugs removed in Step 1.
NOTE:
De-energize the compressors before taking any test
measurements to ensure a dry indoor coil.
035-16004-001-A-0202
Unitary Products Group
9
B1HA Coil Delta
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0
500
1000
1500
2000
2500
Airflow (CFM)
D
el
taS
ta
tic(
IW
G
)
B1HA018
B1HA024
B1HA042
B1HA030-36
B1HA048-60
Linear (B1HA018)
Linear (B1HA024)
Linear (B1HA030-36)
Linear (B1HA042)
Linear (B1HA048-60)
B1HA024
B1HA030-36
B1HA018
B1HA048-60
B1HA042
