Specifications

13
ENVISION COMMERCIAL SPECIFICATION CATALOG
Standard Premier Microprocessor
The Premier control system is a microprocessor-based
printed circuit board conveniently located in the unit
control box for accessibility. The microprocessor control is
specifically designed for the Envision Series heat pumps
and integrate single speed and dual capacity compressors,
variable speed ECM blower motors and advanced features
needed in geothermal applications. All ECM airflow
selections are conveniently configured on the control via
DIP switches. The microprocessor provides control of the
entire unit as well as outputs for status modes, faults, and
diagnostics. Removable low voltage thermostat terminal
strips provide convenient field connections. LEDs are
located on the front of the cabinet for quick inspection
without removing any access panels.
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 blower 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.
Fault Retry
All faults (except for low RPM faults with the ECM2 blower
motor) 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.
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.
Heating Operation
Heat, 1st Stage (Y1)
The blower 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 blower
is switched to medium speed 15 seconds after “Y1” input
(ECM only).
Envision Controls - Premier