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SECTION 28 - HEAT RECOVERY
FORM 160.54-M1
ISSUE DATE: 10/25/2019
JOHNSON CONTROLS
JCI COMPANY CONFIDENTIAL
28
• Control Valve Output Settings:
a. TYPE – Makes the control signal to the Heat
Recovery Control Valve either 0 to 10 VDC
or 4-10mA (default 0 to 10 VDC).
b. PID OUTPUT – Makes the control signal to
the Heat Recovery Control Valve either Di-
rect or Reverse acting (default Direct). Set to
Direct for this application.
c. SET – Is used to manually set the Heat Re-
covery Control Valve to any position be-
tween 0.0% and 100%.
d. AUTO – Returns the Heat Recovery Control
Valve to Automatic Control Mode (default
Auto).
• Hot Water Control – Sets the proportional gain of
the control:
P – Sets the proportional gain of the control
over the range of 0.00 to 5.00(default 2.00)
I – Sets the integral gain of the control over
the range of 0.0 to 5.00 (default 2.00)
D – Sets the derivative gain of the control
over the range of 0.0 to 5.00 (default 0.00)
•
Remote Input Type – Configures the LTC I/O
Board input (TB9-3/4) to accept either a 0-10
VDC or 4 to 20mA input signal type for the Re-
mote Hot Water setpoint input.
When Hot Water Control is active, the Control Valve
Output is modulated by a direct acting PID control.
The inputs to the PID control are the Leaving Heat-
ing Condenser Water Temperature and the Hot Water
setpoint (the Active Hot Water setpoint displays the
setpoint in use). The PID control error is defined as
(Hot Water setpoint – Leaving Heating Condenser Wa-
ter Temperature). The PID control’s proportional, inte-
gral and derivative gains are programmable using the
CHANGE SETPOINTS key. The Control Valve posi-
tion is displayed as 0.0% to 100% in the box labeled
CONTROL VALVE OUTPUT. The control output to
the valve is Direct Acting (when the Leaving Heating
Condenser Water Temperature rises above the Hot Wa-
ter Setpoint, the valve is driven more open to provide
greater cooling to the standard lower tube bundle). The
following diagram shows the PID controller.
FIGURE 93 -
PID CONTROLLER DIAGRAM
LD27941
+
-
PID
Control
Error
Analog
Output
Conditioning
PID Control
Output
Analog
Output
Hot Water Setpoint
Leaving Heating
Condenser Water
Temperature
(0.0–100.0%)
(0-10V,
10-0V,
4-20mA [2-10V],
20-4mA [10-2V])
P
I
D
(PID Gains)
Type
(0-10V,
4-20mA)
Output
(Direct,
Reverse)