FORM 150.66-NM2
ISSUE DATE: 09/25/2020
135
JOHNSON CONTROLS
SECTION 8 - UNIT OPERATION
8
PROGRAMMING YCAL0012 - 0021
Condenser fan control type must be programmed under
both the OPTIONS and PROGRAM keys when a VFD
is installed on the chiller. Under the OPTIONS key, FAN
CONTROL must be programmed for DISCHARGE
PRESSURE CONTROL only. This will ensure
condenser fan control of the chiller is solely by discharge
pressure, with no ambient control.
Under the PROGRAM Key, the FAN CONTROL ON
PRESSURE should be programmed for 240 psig and
the FAN DIFFERENTIAL OFF PRESSURE must be
programmed for 80 psig.
Programming as suggested ensures the chiller control
points for the second fan in the fan staging sequence
and the inverter control points are matched for optimum
control of the fans at reduced ambient temperatures,
assuring superheat and oil control is not compromised.
When the chiller and VFD fan control points are
programmed properly, the fans will operate as outlined
in
FAN STAGE
ON
OFF
CONTACTOR MICROBOARD FAN #
SYS 1
SYS 1
SYS 1
1:
VFD Control
(1 fan
Variable Speed)
Fan Speed
Is A Function Of
liquid Temperature
Fan will turn on when
liquid temperature is
above 65
º
F
FAN Will Turn OFF
When liquid
Temperature Drops
Below 65°F
7M
TB7-3
1
2:
1 Fan VFD
Control
2nd Fan
Full Speed
Under Contactor
Control
280 psig,
Both Fans
Will Be Running Full
Speed
Discharge
Pressure
< 200 psig (Pressure Is
< Fan Control ON Pres-
sure of
280 psig Minus Fan
Differential
Pressure of 80 psig =
200 psig)
Fan 1 Will Still
Be Running
7M & 8M
TB7-3 & TB7-10
1 & 3
TABLE 21 – YCAL0012 - 0021 VFD LOW AMBIENT OPTION - CONDENSER FAN CONTROL OPERATION
Summary of Contents for YCAL0012EC
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