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ENVISION SERIES INSTALLATION MANUAL
Cooling Operation
In all cooling operations, the reversing valve directly
tracks the “O” input. Thus, anytime the “O” input is present,
the reversing valve will be energized.
Cool, 1st Stage (Y1,O)
The blower motor and hot water pump are started immediately,
the loop pump(s) is energized 5 seconds after the “Y1” input is
received. The compressor will be energized (on low capacity for
Dual Capacity units) 10 seconds after the “Y1” input. The ECM
blower will shift from low to medium speed 15 seconds after the
“Y1” input (85% of medium speed if in dehumidication mode).
Cool, 2nd Stage (Y1, Y2, O) Single Speed Units
The fan changes to high speed (85% of high speed if in
dehumidication mode) 15 seconds after the “Y2” input (ECM only).
Cool, 2nd Stage (Y1, Y2, O) Dual Capacity Units
The second stage compressor will be activated 5 seconds
after receiving a “Y2” input as long as the minimum rst stage
compressor run time of 1 minute has expired. The ECM blower
changes to high speed 15 seconds after the “Y2” input (85% of
high speed if in dehumidication mode). The Comfort Alert will
delay the second stage compressor until 5 seconds after it
receives a “Y2” from the board.
Fan (G only)
The fan starts on low speed (PSC ON). Regardless of fan
input “G” from thermostat, the fan will remain on low speed for 30
seconds at the end of each heating, cooling or emergency heat
cycle.
Lockout Conditions
During lockout mode, the appropriate unit and thermostat
lockout LEDs will illuminate. The compressor, loop pump, hot
water pump, and accessory outputs are de-energized. The fan will
continue to run on low speed. If the thermostat calls for heating,
emergency heat operation will occur.
Comfort Alert lockouts cannot be reset at the thermostat.
All other lockout modes can be reset at the thermostat after
turning the unit off, then on, which restores normal operation but
keeps the unit lockout LED illuminated. Interruption of power to
the unit will reset a lockout without a waiting period and clear all
lockout LEDs.
High Pressure
This lockout mode occurs when the normally closed safety
switch is opened momentarily (set at 600 PSI).
Low Pressure
This lockout mode occurs when the normally closed low
pressure switch is opened for 30 continuous seconds (set at 40 PSI).
A low pressure fault may also be indicated when a Comfort Alert
lockout has occurred.
Freeze Sensing (Water Flow)
This lockout mode occurs when the freeze thermistor
temperature is at or below the selected freeze point (well 30°F or
loop 15°F) for 30 continuous seconds.
Microprocessor Control (cont.)