Specifications

20
ENVISION COMMERCIAL SPECIFICATION CATALOG
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 control-
ler 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 opera-
tion 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 (AI-5)
The freeze detection sensor will monitor the liquid refrig-
erant temperature entering the water coil in the heating
mode. If the temperature drops below the freeze detection
trip point for the recognition delay period, the condition
will be recognized as a fault. The freeze detection trip
point will be factory set for 30°F and will be field select-
able for 15°F by removing a jumper wire on BI-5. The
freeze detection fault condition will be bypassed 2 minutes
at normal compressor startup, to allow the refrigeration
circuit to stabilize. If the freeze detection sensor becomes
unreliable at any time compressor operation will imme-
diately 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 compres-
sor 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 con-
densate 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 En-
abled” 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.
Envision Controls - FX10 cont.