T Therm Geo TST-***, Installation & Operating Instructions Manual

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12/03/2012
40 GI301
Operational Tips
GEO Logic -
The GEO Logic board performs the functions controlling the compressor operation, system
lockout, compressor anti-short cycle, and a three minute delay after power is applied.
Review Operational Indicator section of this manual before proceeding.
Pump/Blower Purge –
a Y-stat input starts the blower motor, loop source pump, open loop solenoid, and
desuperheater pump. The stat-Y action input to CSL is delayed by 5 seconds. These four items allow for
“circulation” before the compressor is turned on. The blower motor has a 45-second turn on ramp thus it will not
be noticeable during this 5-second start purge.
After the time delay expires, the compressor contactor will be energized as long as the high and low pressure
switches are closed. If either switch is open after the delay expires, the compressor will not energize. If either
switch opens while the compressor is energized, it will de-energize immediately and begin the anti-short cycle
delay. The compressor will not be allowed to turn on again until the 2 X ACD (6 minutes) expires and both
pressure switches are closed. If the GEO Logic controller experiences three high pressure, low pressure soft
lockouts in a single thermostat call period, it will hard lock out the compressor. During both hard and soft
lockouts the fault codes are displayed.
The flow switch has a bypass timer in which the GEO Logic board will ignore an open flow switch for the first
15 seconds. If the flow switch opens the GEO Logic controller will de-energize the compressor and initiate a
single soft lockout. If the GEO Logic controller experiences a second flow switch fault during a single
thermostat call period, it will hard lock out the compressor.
NOTE
This is a fluid flow switch; it is not a GPM sensor for determining adequate flow. It is only an indicator, and
cannot be used to determine sufficient flow.
A manual reset of power will be required to reset any hard lockout condition.
At stat-Y end, loop source pump, desuperheater pump, and solenoid turn off immediately.
Problems that could cause a lockout situation include:
1. Source water flow problems
2. Hydronic water flow problems
3. Internal heat pump operation problems
4. Excessive cold water temperature conditions, source and load
5. Excessive hot water temperature conditions , source and load
6. Under Voltage (source voltage less than 195 volts)
The GEO Logic control has a CSL Fault Count LED to indicate which type of fault or lockout has occurred.
The ACD function puts a time-out period of
3
minutes on the compressor before re-starting on a normal cycle.
This function protects the compressor from repeated on/off operation in the event of a loose wire or faulty
thermostat.