Table of Contents
Advertisement
OPERATION
REMOTE TEMPERATURE RESET CONTROL
Temperature Reset Control
Temperature Reset Control is used to reset the actual
LCHLT (Leaving Chilled Liquid Temperature) setpoint
used in capacity control. There are several ways to
change the LCHLT setpoint. The first is by re-program-
ming the Local Cooling Setpoint under the SETPOINTS
key. This is the value the unit will control the LCHLT
to if neither of the other methods is active.
Remote Temperature Limit Reset is only possible if the
option is enabled by both the OPTIONS Key selection
and in the factory programmable password protected
Unit Setup Mode.
Remote ISN Setpoint Control
The Remote Leaving Chilled Liquid Setpoint Cooling
Setpoint can be set via the ISN comms. The control
panel will only accept a remote setpoint from the ISN
if the control panel is in Remote Control Mode (under
the OPTIONS KEY). If the control panel is in Local
Control Mode, the ISN setpoint will be ignored and the
Remote Cooling Setpoint is set to the Local Cooling
Setpoint. The minimum and maximum allowable reset
values will be the same as the minimum and maximum
allowable programmable values for the Local Cooling
Setpoint. If these values are exceeded by the ISN, the
minimum or maximum value will be used.
Contact a local YORK ISN Representative for details
on ISN controls and capabilities.
Remote Temperature Reset
The Remote Leaving Chilled Liquid Cooling Setpoint
can be reset via the Remote Temperature Reset analog
input. A zero signal input (0% input) equates to a 0°F
offset to the Local Cooling Setpoint. A full scale sig-
nal input (100% input) equates to a "positive" offset to
the Local Cooling setpoint equal to the programmable
Maximum Remote Temp Reset. The offset is linear
and may be adjusted anywhere between the 0% and
100% points. The maximum setpoint allowed is the
maximum programmable Local Cooling Setpoint and
will be capped at this value, if the calculated setpoint
with temperature offset exceeds this value.
160
This input may be used either in Local or Remote Con-
trol Mode. This feature will only operate if enabled
under the UNIT SETUP and the OPTIONS Key. The
input will be ignored if the Remote Temp Reset is dis-
abled under the OPTIONS key or if there are valid ISN
comms while in Remote Control Mode. Once a change
to the input is registered, a timer is set to the value of
the Remote Inputs Service Time as programmable un-
der the Unit Setup Mode at the factory for the default
value of 15 minutes. The low limit is 5 minutes and
the high limit is 60 minutes.
be ignored until this timer expires. The timer assures
that rapid changes in a remote reset signal don't result
in poor temperature control or excessive compressor
cycling. In most instances, this timer will not need to
be changed, since reset more often than 15 minutes will
create problems with chilled liquid temperature control.
Factory Service should be contacted if a timer change
is required.
Control Board jumper JP4 must be positioned correctly
to receive either a voltage (0-10VDC or 2-10VDC) or
current (0-20mA or 4-20mA) signal. Place the jumper
in the "V" position for a voltage signal or mA for a
current signal (See FIG. 14, P106). The software must
be configured under the OPTIONS key for the specific
type of input signal to be used.
The maximum temperature reset is achieved at either
10 VDC or 20 mA. Sending the minimum signal (0
VDC, 2 VDC, 0 mA, or 4 mA based on the OPTIONS
key setting) causes the setpoint to revert back to its lo-
cal programmed value. If the setpoint reset causes the
setpoint to go over the maximum programmable value,
it will be set to the maximum programmable setpoint.
FORM 201.21-NM2 (616)
The Remote input will
JOHNSON CONTROLS
Advertisement
Table of Contents
