Dwyer 8B - Manual (Page 10)

Page 10
Heating, Cooling or Dual Loop Control
Temperature Control can be achieved by either heating or cooling. In the B series controllers,
heating and cooling can be operated simultaneously using Dual Loop Output Control to
maintain a temperature set point. When Dual Loop Output Control is used, control outputs
must be connecting to the heating and cooling devices. Please refer to the following for the
operation of each setting.
Control Modes are selected by changing the S-HC parameter in the Initial Setting Mode.
Select HEAt, for heating or reverse acting control for output 1. If selected, output 2 will
become alarm 3.
Select CooL, for cooling or direct acting control for output 1. If selected, output 2 will become
alarm 3.
Select H1C2 or C1H2 for Dual Loop Output Control for output 1 and 2. If H1C2 is selected,
output 1 would be fore heating or reverse acting control and output 2 would be for cooling or
direct acting control. If C1H2 is selected, output 1 would be for cooling or direct acting control
and output 2 would be for heating or reverse acting control.
Setting the control mode to PID when the controller is set for Dual Loop Output Control
Activates the Proportional Band Coefficient (CoEF) parameter and the Dead Band (dead)
parameter.
The Proportional Band Coefficient (CoEF) sets the Proportional band value for Output 2
based on the Proportional band of output 1. The Proportional Band of Output 2 would be
equal to the Proportional Band (Pn) of Output 1 multiplied by the Proportional Band
Coefficient (CoEF). The Integral Time (in) and the Derivative Time (dn) will be the same for
both Outputs.
The Dead Band (dEAd) parameter sets an area in which the heating and cooling outputs are
operating at 0% on. The Dead Band is centered on the Set Point in Dual Loop Output Control
mode. Please see the Dead Band illustrated on page 19.