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Greensource CDi Series TW Model
Heating Mode
When the unit is operated in the heating mode and
the controlled-water temperature is below the set
point minus the differential setting, terminal Y1
will close and the unit will operate (first stage
compressor in a two stage unit). When the set
point is satisfied, the compressor is turned off. In
a two-stage unit after the first activation if the
water temperature drops an additional two
degrees below the set point, the second stage
(terminal Y2) will be activated (if the control is
configured for both compressors). Both stages will
be on until the set point is satisfied. When the
units runs after power is applied or the mode is
changed from cooling to heating, if the fluid
temperature is below set point and does not
change for five minutes, the second stage of
heating will be activated. This only applies for a
two-stage machine. There will be a five-minute
delay on a break after the unit cycles off on
temperature, a power interruption, or because of a
fault condition. At any point in time the control will
ignore a low-pressure switch condition for 120
seconds before turning off the compressor.
Cooling Mode
When the unit is operated in the cooling mode and
the leaving-water temperature is above the
temperature set point plus the differential setting,
terminals Y1 will close (first stage compressor of a
two-stage unit) and the unit will operate in the
cooling mode. When the set point is satisfied the
compressor is turned off. The reversing valve is
always activated when the unit is in the cooling
mode.
On two-stage units, after first-stage activation if
water temperature increases two degrees above
the set point, the second stage (terminal Y2) will
be activated (if control is configured for both
compressors). Both stages will remain on until the
set point is satisfied.
When the unit runs after power is applied or the
mode is changed from heating to cooling, if fluid
temperature is above cooling point and does not
change for three minutes, the second stage of
cooling will be activated. this only applies for a
two-stage machine. There will be a five minute
delay on break after the unit cycles off on
temperature, a power interruption, or because of a
fault condition.
Greensource CDi Series TW Model
Auto-Changeover Mode
The controller's auto-changeover mode control
feature will switch from the heating mode to
cooling mode and vice versa based on the setting
of the change-over sensor. There will be a dead
band where the control will not call for either heat
or cool. The dead-band setting is adjustable in the
configuration mode. When the auto-changeover
mode is selected, the changeover set point will be
displayed for five seconds; however, this point is
only adjustable when the controller is in the
configuration mode. Once the controller has
switched to either heating or cooling mode,
pressing the up or down buttons will display the
set point for that particular mode. When the
reading from the changeover sensor is above the
changeover set point plus the dead-band setting,
the unit will operate in the cooling mode and will
maintain the cooling set-point temperature. While
in the cooling mode, the user can adjust the
cooling set point. Likewise when the changeover
sensor is below the changeover set-point minus
the dead band setting, the unit will switch to the
heating mode and will maintain the heating
set-point temperature. While in the heating mode
the user can adjust the heating set point. Once the
reading from the sensor enters the dead-band
zone, it will terminate the call for cooling or
heating even if the set points are not satisfied.
Mode switching will be HEAT – COOL – OFF in a
closed loop. If the changeover sensor is shorted
when the control is in auto-changeover mode then
the control will switch to the OFF mode. If no
sensor is connected, the controller will indicate a
sensor error code.
Unit Protection
The unit controller will protect the unit against a
high or low pressure condition and brownout. To
avoid nuisance lockouts, an intelligent reset
function is built into the controller to allow the unit
to restart one time in the event of a fault condition.
If a fault condition is initiated on any circuit, the
corresponding compressor will be turned off and
the five-minute delay on the break time period
timer is initiated. After the delay expires, the unit
will attempt to restart. If the fault condition still
exists or reoccurs within the next 60 minutes, the
unit will go into a hard lockout and requires a
manual lockout reset. During this period the fault
LED will indicate the cause of the fault.
Subject to change without prior notice
Water-To-Water Unit Controller | 23
8733954853 (2020/04)
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