Step 5 Ð Con®gure Unit for Minimum Load Con-
trol Ð Once the piping installation and wiring installation are complete, the chiller must be con®gured for minimum load control operation. This may be done using the unit key- pad
1.Press 
on the keypad.
2.Press the down arrow 
until the display reads:
MIN. LOAD VALVE SELECT DISABLE
3.To enable the minimum load valve feature, press
.
4.The display may read as follows. (If not, skip to Step 7.)
PASSWORD PROTECTED FUNCTION ENTER PASSWORD
5.Press 
.
6.The
MIN. LOAD VALVE SELECT DISABLE
7.Press 
. The display changes to:
MIN. LOAD VALVE SELECT ENABLE
The chiller is now con®gured for minimum load valve control.
Step 6 Ð Test Minimum Load Relay Outputs
ÐAfter the accessory components are installed and the unit is recharged and recon®gured, test the operation of the relay and solenoid valve using the Quick Test software function. Test Circuit A as follows (the LOCAL/OFF switch must be in the OFF position):
1.Press 
on the
2.Press the down arrow 
until the display reads:
MIN. LOAD VALVE A RELAY IS OFF
3.Press 
.
4.The display may read as follows. (If not, skip to Step 7.)
PASSWORD PROTECTED FUNCTION ENTER PASSWORD
5.Press 
.
6.The
MIN. LOAD VALVE A RELAY IS OFF
7.Press 
to energize the relay. The display reads:
MIN. LOAD VALVE A RELAY IS ON
An audible click will be heard. Verify that the solenoid valve for Circuit A is energized.
8.Press 
to turn off the minimum load valve relay for Circuit A.
To check the operation of the solenoid valve on Circuit B, follow the same procedure as the preceding, but enter
enter 
in Step 1, instead of 
. The display screens will be for Circuit B instead of A.
After testing is complete, recheck all electrical connec- tions for proper location and tightness. For 30HX units, re- place and secure the access panels for the unit control box. For 30GX units, secure the junction box covers to the junc- tion boxes.
Step 7 Ð Adjust Setting of Minimum Load Ball
Valve Ð Before the installation is complete, the mini- mum load ball valve must be adjusted to suit the application. Calibrate one circuit at a time as follows:
1.Adjust the ball valve so that it is approximately half open.
2.Operate the chiller in Manual Control mode, with one cir- cuit operating, and all compressor loaders deenergized.
NOTE: Operation of the chiller in Manual Control mode is described in the Controls,
3.Record the cooler DT (the difference between cooler en- tering ¯uid temperature and cooler leaving ¯uid tempera- ture) at this fully unloaded condition.
4.Use the Manual Control feature to enable the minimum load valve for the circuit that is operating.
5.Observe and record the cooler DT with the minimum load valve energized.
6.Adjust the minimum load ball valve until the cooler tem- perature difference reading from Step 5 is equal to half of the temperature difference reading from Step 3.
7.Open the ball valve to decrease the temperature differ-
ence or close the ball valve to increase the temperature difference (DT). When the valve is adjusted correctly, the difference between cooler entering and leaving ¯uid temperatures when the minimum load control is ener- gized must be at least half of the temperature difference when the minimum load control is deenergized. For ex- ample, if the difference between the cooler entering and leaving water temperature is 3° F with the valve deen- ergized, then the difference between cooler entering and leaving water temperature must be at least 1.5° F with the valve energized.
Once the outputs have been tested and the ball valve ad- justed, the installation is complete.
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