York YCAS Installation Operation & Maintenance page 141

Wiring from remote "dry" contact (for
re set func tions) should not ex ceed 25
ft. (8 m) and should be run in ground ed
con duit that does not carry any wir ing
oth er than con trol wiring or shield ed
cable. If an in duc tive de vice (relay,
contactor) is sup ply ing these con tacts,
the coil of the device must be sup-
pressed with a sup pres sor YORK Part
Num ber 031-00808-000 across the
in duc tive coil.
Remote Current Reset must never be
used to control temperature. These
contacts are to be used only for peri-
odic demand limiting purposes.
Remote Setpoint Temperature Reset
The chilled liquid leaving temperature setpoint pro-
grammed into the micro can be remotely adjusted to
a higher value using repeated timed closure of "dry"
con tacts connected to Terminals 13 and 17 of TB4
located in the log ic section of the control panel (See
Section 8.1.12). The du ra tion of the contact closure will
determine the amount of ad just ment. This is achieved
as follows:
The maximum allowable reset value can be pro grammed
from 2°F - 40°F (1°C - 22°C), as appropriate to the
ap pli ca tion - see Section 6.4. Once the max i mum reset
is pro grammed, an input contact closure of 11 seconds
pro vides the maximum reset. Closure for less than 11
sec onds will provide a smaller reset. For noise im mu ni ty,
the micro will ignore closures of less than 1 sec ond. To
compute the necessary contact clo sure time to provide
a required Reset, use the following steps:
Reset Temp ={ (Contact Closure - 1sec) X Programmed Max Reset}
Offset
For example, with a programmed setpoint of 44°F (7°C),
after a 4 second pulse and a programmed maximum off set
of 40°F (22°C), the temperature offset would equal:
Reset Temp = (4 sec - 1 sec) X 40°F
10 sec
Reset Temp = 120°Fsec
10 sec
= 12°F (6°C)
To determine the new setpoint, add the reset to the
setpoint programmed into mem o ry. In the example
above, if the pro grammed setpoint = 44°F (7°C), the
YORK INTERNATIONAL
10 sec
new setpoint after the 4 sec ond contact clo sure would
be 44°F (7°C)+ 12°F (6°C) = 56°F (13°C). This new
setpoint can be viewed on the display by pressing the
Re mote Reset Tem per a ture/Range key.
To maintain a given offset, the contact clo sure signal
must be repeated (refreshed) every 30 sec onds - 30
minutes. The refresh is not ac cept ed soon er than 30
sec onds from the end of the last PWM signal, but must
be refreshed be fore 30 minutes has elapsed. After 30
minutes, if no re fresh is provided, the setpoint will
change back to its orig i nal value.
After an offset signal, the new Re mote
Setpoint may be viewed by pressing the
Re mote Cooling Setpoint Key. How-
ev er, if this dis play is be ing viewed
when the reset pulse occurs, the set-
point will not change on the dis play.
To view the new offset, first press
any oth er dis play key on the key pad
and then press the Re mote Cooling
Setpoint key. The new setpoint will
then ap pear.
Remote Setpoint Reset will not op-
er ate when a Re mote Control Center
Option Kit is con nect ed to the Micro.
The Remote Control Center will al ways
de ter mine the setpoint.
Wiring from remote "dry" contact (for
reset func tions) should not exceed 25 ft.
(8 m) and should be run in ground ed
con duit that does not car ry any wir ing
oth er than control wir ing or shield ed
ca ble. If an in duc tive de vice (re lay,
contactor) is sup ply ing these con tacts,
the coil of the de vice must be sup pressed
with a sup pres sor YORK Part Num ber
031-00808-000 across the in duc tive
coil.
Remote Setpoint Reset must never be
used to control temperature. These
contacts are to be used only for oc-
casional temperature setback due to
outside ambient, changes in building
occupancy, or ice storage.
FORM 201.19-NM6 (804)
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