Quantech QWC3050T-200T, Installation Operation & Maintenance

Page: 151 / 186

SECTION 8 – UNIT OPERATION
FORM QWC3-NM1
ISSUE DATE:11/20/2020
QUANTECH
151
8
(English)
(6 sec. - 1) (10°F/10) = 5°F Reset
So, the new chilled liquid setpoint = 45°F + 5°F=
50°F. This can be viewed by pressing the COOLING
SETPOINTS key twice. The new value will be dis-
played as “REM SETP = 50.0°F.”
(Metric)
(6 sec - 1) * (5.56°C/10) = 2.78°C
Reset Cooling Setpoint = 7.22°C + 2.78°C = 10.0°C
So, the new reset Cooling Setpoint = 7.22 °C + 2.78°C
= 10°C. This can be viewed by pressing the COOL-
ING SETPOINTS key twice. The new value will be
displayed as “REM SETP = 10.0°C.”
* Max Reset Value is the “Max EMS-PWM Remote Temp. Reset”
setpoint value described in the programming section under Cooling
Setpoints. Programmable values are from 2°F to 40°F (1.11°C to
22.22°C).
BAS/EMS TEMPERATURE RESET USING A
VOLTAGE OR CURRENT SIGNAL
The Remote Reset Option allows the Control Center
of the unit to reset the chilled liquid setpoint using a
0 - 10VDC input, or a 4-20mA input connected to
CTB1 terminals A- and A+. Whenever a reset is called
for, the change may be noted by pressing the COOL-
ING SETPOINTS key twice. The new value will be
displayed as “REM SETP = XXX °F.” This reset value
is always added to the locally programmed chilled liq-
uid setpoint, meaning this function never lowers the
chilled liquid setpoint below the locally programmed
value.
If a 0 - 10VDC signal is supplied, it is applied to termi-
nals A+ and A-, and jumper JP1 on the I/O board must
be inserted between pins 2 and 3. To calculate the reset
chilled liquid setpoint for values between 0VDC and
10VDC use the following formula:
Setpoint = Local Chilled Liquid Se °Reset
°Reset = (DC voltage signal) x (*Max Reset Value)
10
Example:
Local Chilled Liquid Setpoint = 45 °F (7.22 °C)
*Max Reset Value = 20 °F (11.11 °C)
Input Signal = 6VDC
(English)
°Reset = 6VDC x 20 °F = 12 °F Reset
10
New Setpoint = 45 °F + 12 °F = 57 °F
(Metric)
°Reset = 6VDC x 11. 11 °C = 6.67 °C Reset
10
New Setpoint = 7.22 °C + 6.67 °C = 13.89 °C
* Max Reset Value is the “Max EMS-PWM Remote Temp. Reset”
setpoint value described in the program ming section under Cooling
Setpoints. Programmable values are from 2 °F to 40 °F (1.11 °C to
11.11 °C).
If a 4-20mA signal is supplied, it is applied to termi-
nals A+ and A- and jumper JP1 on the I/O board
must be installed between pin 1 and 2 . To calculate
the chilled liquid setpoint for values between 4mA and
20mA use the following formula:
Setpoint = Local Chilled Liquid Se °Reset
°Reset = (mA signal - 4) x (*Max Reset Value)
16
Example:
Local Chilled Liquid Setpoint = 45° (7.22 °C)
*Max Reset Value = 10 °F (5.56 °C)
Input Signal = 12mA
(English)
°Reset = 8mA x 10 °F = 5 °F Reset
16
Setpoint = 45 °F + 5 °F = 50 °F
(Metric)
°Reset = 8mA x 5.56 °C = 2.78 °C Reset
16
Setpoint = 7.22 °C + 2.78 °C = 10.0 °C