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EKW FX10 INSTALLATION MANUAL
3.8.2. S-Plan Mode
This mode allows externally selectable separate operation of domestic hot water or comfort conditioning.
If only the Y1/System Enable input (BI-7) is enabled, the heat pump will not enter cooling mode. If the S-Plan
Select Enable (BI-10) is enabled and the Y1/System Enable input (BI-7) is not enabled, the reversing valve
will be positioned for cooling. Compressor operation will be setpoint controlled based on the relationship of
the load entering water temperature and the setpoint. If both the Y1/System Enable (BI-7) and S-Plan Comfort
Select Enable (BI-10) are enabled, during the cooling cycle, the reversing valve position will be controlled
by the ’O’ input and the domestic/comfort cycle status. Compressor and reversing valve operation will be
time-shared in order to maintain setpoint temperature in a domestic hot water tank and setpoint temperature
in a chilled water loop suitable for fan coil cooling operation. Primary consideration is given to the domestic
hot water. A domestic hot water heating cycle will end once the setpoint is reached, or after an adjustable
time delay has expired. At the end of a domestic water heating cycle, the position of the load water valve
will be changed via BO-9, and a sampling period will begin for determining comfort cooling needs. If cool-
ing is required, the reversing valve will positioned for cooling and a cooling cycle will begin. If the chilled
water loop entering water temperature is within setpoint requirements, the controller immediately switches
to domestic hot water operation. The compressor will be cycled in response to the load entering water
temperature/setpoint control logic. Accessory output 2 will be commanded on 60 seconds prior to compressor
start and remain on for a delay of 30 seconds after the compressor is turned off-suitable for load loop pump
operation. Accessory output 2 is network and MUI configurable to run continuous if the Y1/System Enable
input is activated, or cycled. After the compressor output is turned off, it will remain off for the time specified in
the compressor short cycle time delay After the compressor output is turned off, it will remain off for the time
specified in the compressor short cycle time delay. Accessory output 1 is cycled with the compressor, suitable
for source loop pump operation.
3.8.3. Aqua-stat Mode
During the cooling cycle, the reversing valve will be positioned for cooling operation. If an aqua-stat is
being used, the aqua-stat will command the reversing valve “On” for cooling. When a Y call is initiated, and
the random restart delay timer is expired, accessory output 2 will turn on. If the compressor short cycle time
delay has satisfied, the compressor and accessory output 1 will turn on after the fixed compressor start delay
timer has been satisfied. When cooling is no longer required, the compressor and accessory output 1 will
be turned off immediately after the compressor minimum on delay has been satisfied. After the compressor
output is turned off, it will remain off for the time specified in the compressor short cycle time delay. Acces
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sory output 2 will be turned off 30 seconds after the compressor stops.
3.9. emergency shutdown
The emergency shutdown mode can be activated by a command from a facility management system or a
closed contact on BI-2. The default state for the emergency shutdown data point is off. When the emergency
shutdown mode is activated, all outputs will be turned off immediately and will remain off until the emergency
shutdown mode is de-activated. The first time the compressor starts after the emergency shutdown mode has
been de-activated, there will be a random start delay present.
3.10. Lockout mode
Lockout mode can be activated by any of the following fault signals: compressor high discharge pressure,
compressor low suction pressure, low water coil temperature limit on the evaporator, and low water flow on either
the source or load sides of the unit. When any valid fault signal remains continuously active for the length of its
recognition delay, the controller will go into fault retry mode, which will turn off the compressor. After the Compres-
sor short cycle delay, the compressor will attempt to operate once again. If three consecutive faults are recognized
in 60 minutes, the unit will go into lockout mode, turning off the compressor and enabling the alarm output until the
controller is reset. The lockout condition can be reset by powering down the controller, by a command from the
facility management system, or through a user interface.
3.11. entering Load Water temperature (Ai-1)
The entering load water temperature sensor will measure the entering water temperature on the load side of
the heat pump. By default, in the setpoint mode, compressor operation is cycled in response to the entering load
water temperature and setpoint relationship.
