Envision R-410A - Microprocessor Control

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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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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 Overow Protection
The Envision control board incorporates an impedance sens-
ing 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overowlockout
LEDbegins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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
and Comfort Alert faults which result in lock-out) are retried twice
beforenallylockingtheunitout.Anoutputsignalismadeavail-
able 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 Justi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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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