44
Unit Start-up and Shut-down Procedures
Important:
Initial unit commissioning start-up must be performed by Trane or an agent of Trane specifically
authorized to perform start-up and warranty of Trane products. Contractor shall provide Trane (or an agent of
Trane specifically authorized to perform start-up) with notice of the scheduled start-up at least two weeks
prior to scheduled start-up.
Sequence of Operation
This section will provide basic information on unit operation for common events. With microelectronic
controls, ladder diagrams cannot show today's complex logic, as the control functions are much more
involved than older pneumatic or solid state controls.
Adaptive control algorithms can also complicate the exact sequence of operations. This section illustrates
common control sequences.
Unit Startup
If the pre-start checkout, has been completed, the unit is ready to start.
1. Ensure the “STOP” key display on the TD7. As necessary, adjust the setpoint values on the TD7 menus
using TU and record it.
NOTICE - Any change of the protection setpoints might result the loss of related guarantee rights
without the authorization or approval from Trane Company.
2. Close the fused-disconnect switch for the chilled water pump.
3. Check the service valves on the oil line and liquid line for each circuit. These valves must be open before
starting the compressors except the service of receiver.
CAUTION - Compressor damage!
Catastrophic damage to the compressor will occur if the oil line shut off valve or the isolation valves
are left closed on unit start-up.
4. Power on the electrical heater of evaporator.
5. Ensure that the Uninterruptible Power Supply to the heaters of compressor oil sump and oil separator has
been operating properly for a minimum of 12 hours before starting. Failure to do so may result in compressor
damage.
6. Select the MODE and press the AUTO key on TD7. If the unit control calls for operation and all safety
interlocks are closed, the unit will start. The compressor(s) will load and unload in response to the leaving
chilled water temperature.
7. Once the system has been operating for approximately 30 minutes and has become stabilized, complete the
remaining start-up procedures, as follows:
1) Check the discharge pressure, suction pressure under Refrigerant Report on the TD7 display after
compressor full loaded. The pressures are referenced to sea level (standard atmospheric pressure is
101.35kPa/14.6960 psia). The approach temperature should be within the range of
2) Check both suction and discharge superheat of the compressor. The discharge superheat should be always
above 10°
C
, while the suction superheat normally in the range of 2°
C
~ 6
°C
at heating mode.
3) Measure the system subcooling. Bubbles in the EXV sight glasses indicate either low refrigerant charge or
excessive pressure drop in the liquid line or a stuck open expansion valve. A clear sight glass alone does not
mean that the system is properly charged. Also check system subcooling, liquid level control and unit
operating pressures.
