Step 5 — Configure Unit for Minimum Load Control — Once the piping installation and wiring installa- tion are complete, the chiller must be configured for minimum load control operation. This may be done using the Navigator. Set the Enable/Off/Remote/Contact switch in the OFF position.
1.Press ESCAPE key until display reads ‘SELECT A MENU
ITEM.’ Press 
key to light up Configuration mode.
Press ENTER . Press 
key to select
2.Press the down arrow 
key to select MLVS NO.
3.To enable the minimum load valve feature, press the
ENTER key.
4.The display may read as follows. (If not, skip to Step 7.)
ENTER PASSWORD
5. Press 1 1 1 1 then ENTER key.
6.The Navigator again displays the following:
MLVS NO
7.Press 
key and keyENTER. The Navigator displays:
MLVS YES
The chiller is now configured for minimum load valve control.
Step 6 — Test Minimum Load Relay Out- puts — After the accessory components are installed and the unit is recharged and reconfigured, test the operation of the re- lay and solenoid valve using the Service Test software func- tion. Test both circuits as follows:
1.Press the ESCAPE key until the Navigator displays ‘SE-
LECT A MENU ITEM.’ Press the 
key and light up the Service Test mode. Press the ENTER key. Press the ENTER key and ‘TEST OFF’ will be displayed with ‘OFF’ flash-
ing. Press the 
key then ENTER key and the Navigator displays ‘TEST ON.’ Switch the Enable/Off/Remote contact switch to the Enable position.
2.The display may read as follows. (If not, skip to Step 4.)
ENTER PASSWORD
3.Press 1 1 1 1 then ENTER key.
4.Press the down arrow 
key to select the ‘COMP’ sub-
mode. Press the ENTER key and 
key to display MLV OFF.
5.Press the ENTER key.
6.Press the 
and ENTER key to energize the relays. The display reads:
MLV ON
An audible click will be heard. Verify that the solenoid valves for both circuits are energized.
7.Press the ENTER , 
and ENTER keys to turn the solenoids off. When finished, exit the Service Test mode (change ‘TEST ON’ to ‘TEST OFF’). Put the Enable/Off/Remote Contact switch in the desired position.
After testing is complete, recheck all electrical connections for proper location and tightness. Replace and secure the access panels for the unit control box.
Step 7 — Adjust Setting of Minimum Load Ball Valve — Before the installation is complete, the minimum load ball valve must be adjusted to suit the application. Cali- brate one circuit at a time as follows:
1.Adjust the ball valve so that it is approximately half open.
2.Operate the chiller in Service Test mode, with one circuit operating, and all compressor loaders deenergized.
NOTE: Operation of the chiller in Manual Control mode is described in the Controls,
3.Record the cooler ∆T (the difference between cooler en- tering fluid temperature and cooler leaving fluid tempera- ture) at this fully unloaded condition.
4.Use the Service Test feature to enable the minimum load valve output.
5.Observe and record the cooler ∆T 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 (∆T). When the valve is adjusted correctly, the difference between cooler entering and leaving fluid tem- peratures when the minimum load control is energized must be at least half of the temperature difference when the minimum load control is deenergized. For example, if the difference between the cooler entering and leaving water temperature is 3° F with the valve deenergized, 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.
Copyright 2000 Carrier Corporation
Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.
Book | 2 | PC 903 | Catalog No. | Printed in U.S.A. | Form | Pg 8 | 102 | Replaces: | |
Tab | 5c |
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