Step 7 - Adjust Evaporator-Fan Speed - Carrier 50HJ008-014 Installation, Start-Up And Service Instructions Manual

Insert the data into the following equations:
T 1 (cfm 1 ) + T 2 (cfm 2 )
cfm 3
cfm 2 = (cfm 3 – cfm 1 )
Therefore:
T 1 (cfm 1 ) + T 2 (cfm 3 – cfm 1 )
cfm 3
Use this equation to determine cfm 1 , which is the
minimum airflow across the economizer.
(T 3 – T 2 ) cfm 3
cfm 1 =
(T 1 – T 2 )
If cfm 1 does not match the desired minimum airflow
from Step 1, readjust the minimum position setting
screw.
8. Determine the enthalpy changeover set point from
Fig. 25. The enthalpy changeover set point should be
set to return the outdoor air damper to the minimum po-
sition when enthalpy rises above the set point. The set-
tings are A, B, C, and D. Set the enthalpy changeover
per the setting in Fig. 25.
9. Replace outdoor-air opening panel using screws from
Step 2. Replace filter access panel. Ensure the filter ac-
cess panel slides along the tracks and is securely en-
gaged. See Fig. 26.
10. Fasten hood top and side plate assembly (Fig. 27) to
outdoor-air opening panel with screws provided and in-
stall bottom stop.
11. Slide outdoor-air inlet screens into screen track on hood
side plate. While holding screens in place, fasten screen
retainer to hood using screws provided. See Fig. 28.
NOTE: Refer to Fig. 29 for economizer barometric re-
lief damper characteristics.
CONTROL POINT
CONTROL
(APPROX. DEG.)
CURVE
AT 50% RH
A 73 (23)
B 70 (21)
C 67 (19)
D 63 (17)
RH — Relative Humidity
NOTE: Temperatures are in Fahrenheit. Temperatures in parentheses are in
Celsius.
Fig. 25 — Enthalpy Settings for Parablade
Economizer
= T 3
= T 3
Fig. 26 — Panels Reinstalled on Unit
Fig. 27 — Outdoor-Air Hood Installed on Unit
Fig. 28 — Filter Installed on Outdoor-Air Hood
Step 7 — Adjust Evaporator-Fan Speed —
just evaporator-fan speed to meet jobsite conditions.
For units with electric heat, required minimum cfm is 2250
for 50HJ008,009 and 3000 for 50HJ012 and 014 with the
following exceptions:
UNIT
UNIT
VOLTAGE
208/230
50HJ012 208/230
and 014
460
50HJ008-
575
014
16
UNIT REQUIRED
HEATER
CONFIG- MINIMUM
kW
URATION CFM
42.4 Horizontal 3200
50.0 Horizontal 3200
Horizontal
50.0 3200
or Vertical
17.0 2800
Horizontal
or Vertical
34.0 2350
Ad-