Sequence Of Operation:
This controls the hot water temperature leaving the steam convertor (H.W.S.) by modulating the steam valve.
The setpoint of the hot water temperature is automaticlly reset from outdoor air drybulb temperature (O.A.T.)
Reset Schedule: The set point reset schedule, and its current set point, is shown on an interactive reset schedule graph. The reset line/curve can be modified at the central monitoring panel.
Current Value Chart:
The measured HWS temperature strip chart is shown that continually plots the hot water temperature during the previous 60 minutes.
Analog Gauges: Gauges are provided on the central monitoring panel that display: Outside air dry bulb temperature(OAT), hot water temperature leaving the convertor(HWS), and the controller output (CO) value to the steam valve.
System Chart:
![]()
Controller Status: A 5-state status pilot light is included for the local controller, shown inside this controller's diagram. 1.) HWS Temperature Setpoint(SP) - When this radio button is checked it overrides the OAT reset and selects a manual mode. 2.) Proportional(P) Value - When this radio button is checked the value is available for change. 3.) Intergral(I) Value (repeats/minute) - When the checkbox is un-checked the integral is is ignored. When the radio button is checked the value is available for change. 4.) Derivative(D) Value - When the checkbox is un-checked the derivative value is ignored. When the radio button is checked the value is available for change. 5.) Steam Valve Position(CO): 0 to 100% - When this radio button is checked it overrides the controller output (CO) and selects a manual mode. Choose the radio button for desired value to adjust. Select the increment, then use the ![]() ![]() |
|
SVG Source: Javascript: |
Heating Hot Water System Control - Strip Chart | |
This example continuosly records the outside air dry bulb temperature(OAT), heating hot water supply temperature(HWS), PID controller output value(CO), plus the desired hot water supply temperature setpoint(SP) at the current minute and during the previous 100 minutes. Simulation: random values updated every 2 seconds (equals 1 minute). |