Trane Thermo King ES300, Installation Manual

Page: 63 / 66

62
SPR and CPR Adjustment Procedures
IMPORTANT: The following applicable procedures must be performed on all new unit installations.
Failure to do so may not allow the unit to operate at its maximum capacity.
NOTE: The following procedures are for initial settings. Sometimes
conditions such as high or low ambient temperatures may require that
the settings be fine-tuned for optimum performance.
Suction Pressure Regulator Valve
(Model 20 and 50 Only)
Model 20 and 50 units are equipped with a suction pressure regulator
(SPR) valve. The valve is used to limit the load on the standby compressor.
This also affects the current draw of the electric motor. Monitor the current
drawn of the electric motor when making this adjustment and keep it at
least 1.5 amps below the overload relay setting. Refer to the Maintenance
Manual for overload relay settings.
1. Install a gauge manifold set on the electric standby compressor. Attach
an additional compound gauge to the suction service port on the copper
tube directly before SPR valve (shown in illustration to monitor suction
pressure at the inlet to the suction pressure regulator.
2. Connect the unit power receptacle to an appropriate electric power
source.
3. Place a jumper wire between the 12 and CHB wires at the defrost
termination switch to ensure the unit will run in Defrost.
4. Start the unit and run it in Defrost on the electric standby compressor
until the pressure on the additional compound gauge attached to the
suction service port stabilizes at a pressure above 45 psig (310 kPa).
5. Check the suction pressure on the gauge attached to the suction service
port at the standby compressor. It should be 39.0 ± 4 psig (269 ± 28
kPa) for 230V 3 phase electric motor, and 24.0 ± 4 psig (165.5 ± 28
kPa) for 230V 1 phase electric motor. If the setting is incorrect, remove
the protective cap and adjust the suction pressure regulator valve to the
correct setting.
6. Remove the gauge manifold set, the additional compound gauge, and
the jumper wire when finished with the procedure.
Suction Pressure Regulator
Typical V-520 RT Refrigeration Module Components
Suction
Service Port
for Road
Compressor