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APPENDIX D
Heat/Cool Option
With the Heat/Cool Option, the controller can control a temperature
application with one input at one main setpoint using two outputs, a
heating output and a cooling output. By using a heating and cooling
output, a process is able to quickly bring the temperature to setpoint in
both directions and to limit the amount of overshoot. The larger the
deviation from setpoint, the more output applied to the system on both
the heating and cooling sides. Heat/Cool control is a very effective way
of controlling exothermic processes, processes that generate their own
heat, or processes where ambient temperature is not adequate or fast
enough in returning a process back to setpoint.
The two outputs on the controller are independent and sent to two dif-
ferent output devices. The controller can be equipped with two of the
same or two different output types. Output #2 can be relay, DC SSR dri-
ver, or 4-20mA DC, regardless of what Output #1 is. Both output types
must be specified when ordering.
The controller controls the cooling side with three additional parame-
ters, TC-2, COOL, and db. See also the programming section.
TC2
Cycle Time (Output #2):
Because Output #2 is not necessar-
ily the same as Output #1, the cycle time may be different
CooL
Proportional Band Coefficient for Cooling:
Because the
cooling power may not necessarily be the same as the
heating power, the cooling proportional band may need to
be different from that of the heating proportional band.
