Quantech QWC4, Installation Operation & Maintenance, Page: 84 / 156

QUANTECH
84
FORM QWC4-NM1 (221)
ISSUE DATE: 02/28/2021
SECTION 6 - OPERATION
Use the ▲,▼,◄, and ► keys to see the multiple dis -
plays under a key. Once the ▲ ▼ keys are pressed and
used for scrolling, pressing the original data key will
return to the first display message displayed under the
data keys.
The keypad uses an overlay to convert the keypad to
various languages.
Keypad Data Entry Mode
Enter Data Entry Mode
For numeric programmable items, enter DATA EN-
TRY by pressing any numbered key, the decimal point,
or the +/- key. The data will be entered, and the cursor
will appear under the position where the data is being
entered.
For non-numeric programmable items, enter DATA
ENTRY by pressing the ◄ or ► key. The cursor will
appear under the first position of the non-numeric
string. Press the ◄ or ► key to change the program -
mable choice.
Exit DATA ENTRY Mode
To exit DATA ENTRY, press the

key or X, then the
cursor will disappear. If the user presses any other key
while in DATA ENTRY, the user has two seconds to
accept or cancel the change.
XXXXXXXXXXX PRESS

TO ACCEPT VALUE OR
X TO CANCEL DATA ENTRY
If the

key was pressed while in DATA ENTRY,
and the numeric value entered was out of range,
the following message will appear for two seconds
followed by the original data display.
XXXXXXXXXXX OUT OF RANGE TRY AGAIN!
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Display
The 80-character (two lines of 40 characters) display
is a Liquid Crystal Display (LCD) used for displaying
unit, system parameters, and operator messages. The
display has an LED backlight for night viewing, and is
viewable in direct sunlight.
BASIC OPERATING SEQUENCE
Start Sequence and Loading
To start the chiller, the following conditions must be
satisfied before the VSD DC BUS PRECHARGE will
take place:
• Unit switch must be ON.
• System switch is ON.
•
Run permissive and flow switch inputs have
closed switches to Terminal 2.
• No unit faults or start inhibits exist.
• System is not faulted or inhibited.
• Daily schedule calls for the chiller to run.
• Leaving chilled liquid setpoint is above the
setpoint high limit (setpoint plus cooling range).
Once the anti-recycle timer times out, the chiller con-
trol system will select the compressors to start, pre-
charge the VSD, and begin operating the compressor.
The compressor speed will be ramped to the minimum
start frequency and will increase speed as needed in an
effort to regulate the Leaving Chilled Liquid Tempera-
ture to meet the required setpoint. In optional HEAT
PUMP MODE, the Leaving Condenser Liquid Tem-
perature is regulated to setpoint.
Anti-Recycle Timer
The anti-recycle timer will be set for 120 seconds
when:
• The control panel is powered up. The timer must
time out before a compressor is allowed to start.
• A system starts. The timer will count down from
the time the motor starts, and it must time out be-
fore another compressor is allowed to start.
• A system shuts down. The timer must time out be-
fore the system is allowed to restart.
Evaporator and Condenser Pump Control
The evaporator and condenser pump dry contacts are
energized when any of the following conditions are
true: