Installation manual

30
ENVISION RESIDENTIAL INSTALLATION MANUAL
Startup
The unit will not operate until all the inputs and safety
controls are checked for normal conditions. At first 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 field
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 Overflow 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 overflow lockout LED begins flashing.
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 flashing. (Refer to the
"Fault Retry" section below.)
Testing
The Envision control allows service personnel to shorten
most timing delays for faster diagnostics. (Refer to DIP
switch SW2-1 in the DIP Switch Settings table.)
Fault Retry
All faults (except for low RPM faults with the ECM2 fan
motor and Comfort Alert faults which result in lock-out) are
retried twice before finally 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 DIP Switches SW2-6 and SW2-7 in the
DIP Switch Settings table.)
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 Justification
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).
Heat, 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 first
stage compressor run time of 1 minute has expired. The
Microprocessor Control