WaterFurnace Series NXW - Manual (Page 24)

24
ENVISION 2 NKW 50Hz REVERSIBLE CHILLER INSTALLATION MANUAL
Power Fail Restart
When the controller is first powered up, the outputs will be
disabled for a random start delay. The delay is provided to
prevent simultaneous starting of multiple heat pumps. Once
the timer expires, the controller will operate normally.
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 unoccupied mode or the emergency shutdown mode.
The delay should not be less than 1 second and not longer
than 120 seconds. If the control is in test mode the random
start delay will be shortened to 5 seconds.
Lead Compressor Start Delay Time
The Lead Compressor Fixed On Delay Time will ensure that
the lead compressor output is not enabled for 90 seconds
after the control receives a call to start the compressor. This
delay is adjustable from 30 – 300 seconds over a BAS or a
MUI. If the control is in test mode the Lead Compressor Start
Delay Timer will be shortened to 5 seconds.
Lag Compressor Start Delay Time
The Lag Compressor Fixed On Delay Time will ensure that
the lag compressor output is not enabled for 90 seconds
after the control receives a call to start the compressor. This
delay is adjustable from 30 – 300 seconds over a BAS or a
MUI. If the control is in test mode the Lag Compressor Start
Delay Timer will be shortened to 5 seconds.
Compressor Minimum On Delay
The compressor minimum on delay will ensure that the
compressor output is enabled for a minimum of five (5)
minutes each time the compressor output is enabled. This will
apply in every instance except in the event the high pressure
switch is tripped, freeze protection, or emergency shutdown
then the compressor output will be disable immediately.
Compressor Minimum Off Delay Time
The compressor minimum off time delay will ensure that
the compressor output will not be enabled for a minimum
of five (5) minutes after it is disabled. This allows for
the system refrigerant pressures to equalize after the
compressor is disabled.
Sequence of Operation
Compressor Lead/Lag
Compressor lead/lag is a standard part of the FX10 control
system. The unit is shipped from the factory with lead/
lag enabled. Lead/lag can be activated through the unit
mounted user interface.
Heating Cycle
The control will run the unit in heating mode when there is a
command on the O/B terminal on the terminal board.
Cooling Cycle
The control will run the unit in cooling mode when there is no
command on the O/B terminal on the terminal board.
MUI Alarm History Reporting
If a fault occurs the fault will be recorded in history for
display on the medium user interface in the History Menu.
Each fault type will be displayed in the history menu with
a number between 0 and 3. A reading of 3+ will mean that
fault has occurred more than three times in the past. The
history menu can be cleared with a power cycle only. Alarm
date and time are not included in the history.