WaterFurnace Envision Low Sill - Manual (Page 27)

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ENVISION LOW SILL CONSOLE INSTALLATION MANUAL
Unit Mounted Control
The user selects either “Heat/Cool” or “Fan Only” on the
mode switch, then either “High” or “Low” at the blower
speed switch. The temperature can be controlled by
rotating the thermostat control knob.
The “Fan Only” setting provides constant blower operation.
In the “Heat” mode, a call for heat by the thermostat
closes the compressor contactor contacts, energizing the
compressor, which will run until the thermostat is satisfied.
In the “Cool” mode, a call for cooling by the
thermostat energizes the reversing valve and closes
the compressor contactor contacts, energizing the
compressor, which will run until the thermostat is satisfied.
If either the low or high pressure safety switches are
opened, the compressor and reversing valve are disabled
by the lockout relay. Unit operation will resume only after
the voltage to the unit is interrupted or the mode switch is
placed in the “Off” position.
Optional Versatec Microprocessor
Control Features
The Versatec microprocessor board provides control of
the entire unit as well as outputs for status modes, faults
and diagnostics. The control system is a microprocessor-
based control board that is located in the unit control box.
This feature is available for either unit mounted controls
or optional remote wall mounted thermostat. A 9-pin low
voltage terminal strip provides all necessary terminals for
the wall mounted thermostat.
Startup
The unit will not operate until all the inputs and safety
controls are checked for normal operating conditions.
Fault Retry
All faults are retried twice before finally locking the unit
out to prevent nuisance service calls.
Component Sequencing Delays
Components are sequenced and delayed for optimum
unit performance.
Emergency Shutdown
A grounded signal to common or connecting 24 VAC to
the ES terminal places the controller into the emergency
shutdown mode. The compressor and blower operation are
suspended while in the emergency shutdown mode.
Condensate Overflow Protection
The board incorporates an impedance liquid sensor at
the top of the condensate drain pan. Upon a continuous
30-second sensing of the condensate, the cooling
operation of the unit is suspended.
Safety Controls
The microprocessor board receives separate signals from
a high pressure switch for safety, a low pressure switch
to prevent loss of refrigerant charge and a low suction
temperature thermistor for freeze detection. Upon a
continuous 30-second measurement of the fault (immediate
for high pressure), compressor operation is stopped.
Controls cont.