WaterFurnace Envisio Series Console - Manual (Page 32)

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ENVISION CONSOLE INSTALLATION MANUAL
Control and Safety Feature Details
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.
Lockout Mode
Lockout mode can be activated by any of the following
fault signals: refrigerant system high pressure, refrigerant
system low pressure, freeze detection, and condensate
overflow. 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 Compressor short cycle delay,
the compressor will attempt to operate once again. If
three consecutive faults occur in 60 minutes during a
single heating or cooling demand, the unit will go into
lockout mode, turning off the compressor, enabling the
alarm output, and setting the blower back to low speed
operation until the controller is reset. If the control faults
due to the low pressure input (BI-3) being open during
the pre-compressor startup check, the control will go into
lockout mode immediately, disabling the compressor from
starting and enabling the alarm output (BO-6). The lockout
condition can be reset by powering down the controller, by
a command from the BAS, or by the holding the ESC and
Return keys on the MUI for 5 seconds.
Freeze Detection Limit (AI-5)
The freeze detection limit sensor will monitor the liquid
refrigerant temperature entering the water coil in the
heating mode. If the temperature drops below the freeze
detection limit trip point for the recognition delay period,
the condition will be recognized as a fault. The freeze
detection limit trip point will be factory set for 30°F and
will be field selectable for 15°F by removing a jumper wire
on BI-5. The freeze detection limit fault condition will be
bypassed 2 minutes at normal compressor startup, to allow
the refrigeration circuit to stabilize. If the freeze detection
limit sensor becomes unreliable at any time compressor
operation will immediately be suspended until the problem
is corrected. This should be displayed as an alarm on the
BAS and the MUI. This alarm will be reported a “Water Low
Temp Limit” fault.
High Pressure (BI-11)
The high-pressure switch shall be a normally closed (NC)
switch that monitors the systems refrigerant pressure. If the
input senses the high-pressure switch is open it must disable
the compressor output immediately and count the fault. The
compressor minimum on time does not apply if the high-
pressure switch opens. The compressor will not restart until
the compressor short cycle time delay has been satisfied.
Low Pressure (BI-3)
The low-pressure switch shall be a normally closed (NC)
switch that monitors the systems refrigerant pressure. The
input shall be checked 15 seconds before compressor start
up to be sure the pressure switch is closed and then ignored
for the first 2 minutes after the compressor output (BO-2) is
enabled. If the switch is open continuously for (30) seconds
during compressor operation the compressor output (BO-2)
will be disabled. The compressor will not restart until the
compressor short cycle time delay has been satisfied.
Condensate Overflow
The condensate overflow sensing circuit will monitor
the condensate level as a resistance input to AI-3. If
the condensate water level rises resulting in the input
resistance rising above the set point for the recognition
delay period, the condition will be recognized as a fault.
The condensate will be subjected to a (30) second
lockout delay which requires that the fault be sensed for a
continuous (30) seconds before suspending unit operation.
Alarm Output (BO-6)
The alarm output will be enabled when the control is in the
lockout mode and will be disabled when the lockout is reset.
Test Mode
Raising the zone temperature input (AI-1) reading to 180–
220°F or by holding the ESC and down arrow keys on the
MUI for 5 seconds will put the control into test mode. In
test mode the random start delay and the compressor
fixed on delay time will both be shortened to 5 seconds
and the reversing valve will be allowed to cycle with out
shutting down the compressor. If an MUI is connected
to the control LED 8 will flash and the words “Test Mode
Enabled” will be shown on the LCD display when the
control is in test mode. Test mode will be disabled after
a power cycle, 30 minute timeout, or by holding the ESC
and Up arrow keys on the MUI.
Sequence of Operation
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
Envision Console Controls cont.