Microprocessor Control - Trane 2GN Series Installer's Manual

2GN SPLIT INSTALLER'S GUIDE

MICROPROCESSOR CONTROL

Startup
The unit will not operate until all the inputs and safety controls
are checked for normal conditions. At fi 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 fi 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.
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 TAMG Series 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 low source water temperature sensing. Upon a
continuous 30-second measurement of the fault (immediate
for high pressure), compressor operation is suspended, the
appropriate lockout LED begins fl ashing. (Refer to the "Fault
Retry" section below.)
Testing
The TAMG Series control allows service personnel to shorten
most timing delays for faster diagnostics.
Fault Retry
All faults are retried twice before fi nally 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 TAMG Series control board allows all inputs and outputs
to be displayed on the LEDs for fast and simple control board
diagnosis.
18
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 Justifi 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 blower motor is started immediately, 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 hot water pump is cycled 30 seconds after
the "Y1" input.
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 fi 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.
Heat, 3rd Stage (Y1,Y2,W)
Dual Capacity Units
The hot water pump is de-energized which directs all heat
to satisfy the thermostat. The 1st stage of resistance heat is
energized 10 seconds after "W" input, and with continuous
3rd stage demand, the additional stages of resistance heat
engage 90 seconds after the fi rst stage.
18-GL07D1-4