ENVISION SERIES INSTALLATION MANUAL
Microprocessor Control
Startup
The unit will not operate until all the inputs and safety controls are checked for normal conditions. At first
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.
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
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
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 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.
Testing
The Envision control allows service personnel to shorten most timing delays for faster diagnostics. (Refer to the Field Selection DIP switch
Fault Retry
All faults 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 the Field Selection DIP Switch
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
Heat, 3rd Stage (Y1,Y2,W) Single-Speed Units
The first 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.
Heat, 3rd Stage (Y1,Y2,W) Dual Capacity Units
The hot water pump is
Emergency Heat (W only)
The fan is started on high speed, and the first stage of resistance heat is energized 10 seconds after the "W" input. Continuing demand will engage the additional stages of resistance heat sequentially every 2 minutes.
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