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ENVISION RESIDENTIAL INSTALLATION MANUAL
Startup
The unit will not operate until all the inputs and safety controls
are checked for normal conditions. At fi rst power-up, a four-minute
delay is employed before the compressor is energized.
Component Sequencing Delays
Components are sequenced and delayed for optimum space
conditioning performance.
Accessory Relay
An accessory relay on the control board allows for fi eld
connection of solenoid valves, electronic air cleaners, etc. The
accessory relay has a normally open output and a normally closed
output.
Short Cycle Protection
The control employs a minimum "off" time of four minutes to
provide for short cycle protection of the compressor.
Condensate Overfl ow Protection
The Envision control board incorporates an impedance sensing
liquid sensor at the top of the drain pan. Upon a continuous
30-second sensing of the condensate, compressor operation is
suspended (see Fault Retry), and the condensate overfl ow lockout
LED begins fl ashing.
Shutdown Mode
A 24VAC common signal to the “shutdown” input on the control
board puts the unit into shutdown mode. Compressor, hot water
pump and fan operation are suspended.
Safety Controls
The Envision control receives separate signals for a high
pressure switch for safety, a low pressure switch to prevent loss
of charge damage, and a low suction temperature thermistor for
freeze sensing. Upon a continuous 30-second measurement of
the fault (immediate for high pressure), compressor operation is
suspended, the appropriate lockout LED begins fl ashing. (Refer to
the "Fault Retry" section below.)
Testing
The Envision control allows service personnel to shorten most
timing delays for faster diagnostics. (Refer to the Field Selection
DIP switch SW2-1 on page 24.)
Fault Retry
All faults (except for low RPM faults with the ECM2 fan motor)
are retried twice before fi nally locking the unit out. An output signal
is made available for a fault LED at the thermostat. The “fault
retry” feature is designed to prevent nuisance service calls.
Diagnostics
The Envision control board allows all inputs and outputs to be
displayed on the LEDs for fast and simple control board diagnosis.
(Refer to the Field Selection DIP Switch SW2-1 on page 24.)
Resistance Heat Control (208-230 Units)
The electric heat control module contains the appropriate
high-voltage control relays. Control signals energize the relays in
the proper sequence, and the LED display board indicates which
stages are energized.
Hot Water High Limit
(Domestic Hot Water Option)
This mode occurs when the hot water input temperature is at
or above 130°F for 30 continuous seconds. The DHW limit status
LED on the unit illuminates and the hot water pump de-energizes.
Hot water pump operations resume on the next compressor cycle
or after 15 minutes of continuous compressor operation during the
current thermostat demand cycle.
Hot Water Justifi cation
Since compressor hot gas temperature is dependant on loop
temperature in cooling mode, loop temperatures may be too low
to allow proper heating of water. The control will monitor water and
refrigerant temperatures to determine if conditions are satisfactory
for heating water. The DHW limit status LED on the unit illuminates
when conditions are not favorable for heating water.
Heating Operation
Heat, 1st Stage (Y1)
The fan motor is started on low speed immediately (PSC
ON), the loop pump is energized 5 seconds after the “Y1” input
is received, and the compressor is energized on low capacity 10
seconds after the “Y1” input. The fan is switched to medium speed
15 seconds after “Y1” input (ECM only). The hot water pump is
cycled 30 seconds after the "Y1" input.
Heat, 2nd Stage (Y1,Y2) Single-Speed Units
The hot water pump is de-energized, which directs all heat
to satisfying the thermostat, and the fan changes to high speed
15 seconds after the "Y2" input (ECM only).
H
eat, 2nd Stage (Y1,Y2) Dual Capacity Units
The second stage compressor will be activated 5 seconds
after receiving a “Y2” input as long as the minimum fi rst stage
compressor run time of 1 minute has expired. The ECM blower
changes from medium to high speed 15 seconds after the “Y2” input.
The Comfort Alert will delay the second stage compressor
until 5 seconds after it receives a “Y2” from the board.
Heat, 3rd Stage (Y1,Y2,W) Single-Speed Units
The fi rst stage of resistance heat is energized 10 seconds
after “W” input, and with continuous 3rd stage demand, the
additional stages of resistance heat engage sequentially
every 5 minutes.
Microprocessor Control