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EKW FX10 INSTALLATION MANUAL
3. Sequence of Operation
3.1. Power Fail restart
When the controller is first powered up, the outputs will be disabled for a random start delay time (See Section
3.2). The delay is provided to prevent simultaneous starting of multiple heat pumps. Once the timer expires, the
controller will operate normally. A restart status variable is available for indication of this occurrence.
3.2. random start delay
This delay will be used after every power failure, as well as the first time the compressor is started after the
control exits the emergency shutdown mode. The default time period for the start delay will be random between 1
and 120 seconds.
3.3. compressor Fixed on delay time
The Compressor Fixed On Delay Time will ensure that the compressor output (B02) is not enabled for (30)
seconds after the control receives a call to start the compressor. This call may originate from an Aqua-stat or from
the internal setpoint control logic.
3.4. Compressor Minimum On Delay
The compressor minimum on delay will ensure that the compressor output is enabled for a minimum of (2)
minutes each time the compressor output is enabled. This will apply in every instance except in the event the
high pressure switch is tripped or emergency shutdown, which causes the compressor output to be disabled
immediately.
3.5. compressor short cycle delay time
The compressor short cycle time delay will ensure that the compressor output will not be enabled for a
minimum of (5) minutes after it is disabled. This allows for the system refrigerant pressures to equalize after the
compressor is disabled.
3.6. Pump Sampling
The load water pump may be set to operate in either Sampled or Continuous mode. In the Continuous mode,
the load pump will run any time unit operation is enabled, both in Setpoint mode and S-Plan. In the Sampled
mode, the load pump will run during all compressor calls, and will cycle in a user-adjustable fashion when no
compressor calls exist, in order to allow a determination of the need to run the compressor. In a domestic cycle,
a pump sample period is 1/2 of the domestic operation cycle length. In a comfort cycle, the sample period is 1/2
of the comfort operation cycle length. The sample length is 200 seconds initially, and is adjustable. In the final 60
seconds of a sample operation, the temperature control logic is allowed to generate a compressor call if indicated
by the temperature/setpoint relationship. Sampling does not apply to Aqua-Stat mode of operation.
3.7. heating Cycle
3.7.1. Setpoint Mode
During the heating cycle, the reversing valve will be positioned for heating 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 either the Y1/System Enable input or the S-Plan input is active or cycled
operation. Accessory output 1 is cycled to operate with the compressor, suitable for source loop pump
operation. Compressor operation will be time-shared in order to maintain setpoint temperature in a domestic
hot water tank and setpoint temperature in a heating water loop suitable for in-floor radiant heating. Primary
consideration is given to the domestic hot water. A domestic hot water heating cycle will end once the set-
point 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 heating cycle for the comfort heating
water loop will begin. If the heating water loop entering water temperature is within setpoint requirements, the
controller immediately switches to domestic hot water operation. After the compressor output is turned off, it
will remain off for the time specified in the compressor short cycle time delay.
