WaterFurnace Envision (XL) - Manual (Page 29)

ENVISION 7-25 TONS INSTALLATION MANUAL
30
Heating Cycle
On a call for heating, the blower enable output and
accessory output 2 will turn on immediately after the
random start delay timer has been satisfied. If the
compressor short cycle time delay has been satisfied,
the compressor will turn on after the blower enable and
accessory output 2 are on and the fixed compressor start
delay timers have been satisfied.
Set Point Control Mode
In set point control mode the reversing valve output
will be disabled. As the temperature drops below the
heating set point and begins to operate in the heating
proportional band, the low capacity compressor
output (BO-2) will be enabled. A PID loop in the
programming of the control will determine when
the full capacity compressor output (BO-4) is to be
enabled. The compressor must be operating in low
capacity for a minimum of 30 seconds before the full
capacity compressor output can be enabled. During
low capacity compressor operation the ECM2.3 blower
will operate in medium speed and will operate in
high speed when the compressor is operating at full
capacity.
Thermostat Control Mode
In thermostat mode the compressor will be cycled
based on Y1 and Y2 calls from a room thermostat.
When the control receives a Y1 command (BI-7) from
the thermostat the low capacity compressor output
(BO2) will be enabled and the ECM2.3 blower will
operate in medium speed. When the control receives
a Y2 command (BI-8) from the thermostat the full
capacity compressor output will be enabled and the
ECM2.3 blower will operate in high speed. During the
heating cycle the reversing valve will be commanded
into the off position.
Cooling Cycle
On a call for cooling, the blower enable output and
accessory output 2 will turn on immediately after the
random start delay timer has been satisfied. If the
compressor short cycle time delay has been satisfied,
the compressor will turn on after the blower enable and
accessory output 2 are on and the fixed compressor start
delay timers have been satisfied.
ECM2.3 Blower Operation
Blower speeds will be selected through the user interface
or the facility management system. There will be a total
of 12 speeds selectable with only three being selected at
any one time. The lowest numbered speed selection set
to ON will select the low-speed blower setting, the middle
selection set to ON will select the medium-speed blower
setting and the highest selection set to ON will select the
high-speed blower setting. If all selections are set to OFF
the software shall select speed setting 10 for low-speed, 11
for medium-speed, and will select speed setting 12 for high
speed. If only one selection is set to ON, that selection
will set the low-speed blower setting, the medium-speed
setting will be 11, and the high-speed setting will be speed
12. The maximum low-speed setting will be speed 10 and
the minimum high-speed setting will be speed 3.
In addition there is a low limit setting in the software to
prevent the ECM2.3 blower speed from being set below
acceptable limits for each unit size.
Network Enabled Output/
Electric Heat Output (BO-5)
This output can be enabled by the BAS network for use as
needed in the field. There is a soft switch in the application
that can be enabled through the BAS or MUI that will allow
this output to be used for auxiliary electric heat. A second
soft switch is available that can be enabled through the
BAS or MUI that will interlock this output with the blower
proving input (BI-6) for operating electric heat. If the
blower proving input is open when the interlock is enabled,
the Electric Heat Output (BO-5) will be immediately
disabled.
If this output is enabled for electric heat then it shall be
used as a backup for the compressor in the event that a
compressor fault occurs during heating operation.
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.
Optional FX10 Microprocessor Control cont