254
FORM 160.54-M1
ISSUE DATE: 10/25/2019
SECTION 31 - HEAT PUMP DUTY
JCI COMPANY CONFIDENTIAL
JOHNSON CONTROLS
Remote Mode, can reset the Leaving Condenser Liquid
Temperature Setpoint below the operator programmed
Local setpoint (see above) while the Heat Pump is in
HEATING Mode. Programmable values are 10, 20, 30
or 40°F(default 10°F). This number is subtracted from
the Local setpoint to create a range over which the re-
mote device can reset the setpoint. For example, if this
setpoint is set for 10°F and the Local setpoint is 90°F,
the remote device can set the Leaving Condenser Liq-
uid Temperature setpoint over the range of 90 to 80°F.
Requires OPERATOR or higher access level.
Leaving Condenser Liquid Temperature
Cycling Offset-Shutdown
Specifies the Leaving Condenser Liquid Temperature
at which the Heat Pump will shutdown on “Leaving
Condenser Liquid – High Temperature” cycling shut-
down in Heating Mode. This is done by defining an off-
set above the Leaving Condenser Liquid Temperature
setpoint. The offset is programmable over the range of
1 – 59°F (default 1°F) above the setpoint, to a maxi-
mum of 125°F. Anytime the Leaving Condenser Liq-
uid Temperature setpoint is decreased, this shutdown
threshold becomes 125°F for the next 10 minutes. Af-
ter 10 minutes, the shutdown threshold becomes the
programmed setpoint offset value. The actual offset
being used is displayed as “Effective Offset” on this
screen. Usually, the offset that is used is the same as
the programmed value. However, the setpoint used can
change automatically to prevent the leaving Condenser
Liquid temperature from going above the maximum al-
lowed temperature of 125°F. For example, if the offset
is set to 6°F but the Leaving Condenser Liquid Tem-
perature setpoint is set to 120°F, the Effective Offset
used will be 5 because 6 would allow it to exceed the
maximum of 125.
Leaving Condenser Liquid Temperature
Cycling Offset-Restart
This specifies the Leaving Condenser Liquid tempera-
ture at which the Heat Pump will restart after a shut-
down on a “Leaving Condenser Liquid Temperature –
High Temperature” cycling shutdown in Heating Mode.
This is done by defining an offset below the Leaving
Condenser Liquid Temperature setpoint. It is program-
mable over a range of 0 to 67°F (default 0°F) below
the Leaving Condenser Liquid Temperature setpoint,
to a minimum of 55°F. The chiller will automatically
restart when this temperature is reached. This setpoint
can be used to reduce chiller cycling by delaying the
Heat Pump restart until the heating load has increased.
Requires OPERATOR or higher access level.
Heating LCHLT (Leaving Chilled Liquid
Temperature) Shutdown
In Heating Mode, the existing “Leaving Chilled Liquid
Temperature – Low Temperature” cycling shutdown
logic will include an additional check to its existing
logic that will cause a shutdown in Heating Mode.
This setpoint allows the user to specify the Leaving
Chilled Liquid Temperature at which the Heat Pump
will shut down on “Leaving Chilled Liquid – Low
Temperature” cycling shutdown when the Heat Pump
is operating in Heating Mode. The low limit for this
setpoint is the higher of (Leaving Condenser Liquid
Temperature setpoint minus 71°F) or (Cooling Mode
Leaving Chilled Liquid Temperature Shutdown Tem-
perature). The high limit for this setpoint is the Leaving
Condenser Liquid Temperature setpoint. The default is
(Leaving Condenser Liquid Temperature setpoint mi-
nus 60°F). The Heat Pump will restart when the Leav-
ing Chilled Liquid Temperature exceeds this shutdown
temperature by 5°F. Requires OPERATOR or higher
access level.
CONTROL
To make Heat Pump duty operational, it must be en-
abled on the SETUP Screen using an ADMIN pass-
word. Once enabled, a HEAT PUMP Screen is acces-
sible from the CONDENSER Screen. All applicable
parameters and setpoints are displayed and maintained
on the HEAT PUMP Screen. The Heat Pump control
can be switched between Heating Mode and Cooling
Mode using the Operational Mode setpoint.
In Heating Mode, the Heat Pump controls the Leav-
ing Condenser Liquid Temperature to the Active Leav-
ing Condenser Liquid Temperature setpoint. In Local
Mode, this is the local keypad entered setpoint. In
ISN, Analog or Digital Remote modes, it is the remote
setpoint input (see above). While running, “System
run – Heating Mode” is displayed on the System Sta-
tus Line and “Heat Pump – Leaving Condenser Liquid
Control” is displayed on the System Details line. If the
Leaving Condenser Liquid Temperature increases to
the Leaving Condenser Liquid Temperature setpoints –
Shutdown threshold, a cycling shutdown is performed
and “Leaving Condenser Liquid Temperature – High
Temperature” is displayed. The Heat Pump will restart
when the Leaving Condenser Liquid Temperature de-
creases to the threshold programmed with the Leav-
ing Condenser Liquid Temperature Cycling Offset –
Restart threshold. To avoid overcooling the Leaving
Chilled Liquid Temperature in Heating Mode, if the
Leaving Chilled Liquid Temperature decreases to the