Heating Loop Controller
The heating controller regulates the status and flow rate of a pump based on building simulation settings. Optionally, the controller can also control a mixing valve.
The controller has 4 (plus 3 optional) analogic inputs.
The controller has 2 (plus 2 optional) outputs, partially digital, partially analogic.
Heating loop cut-in and cut-off are based on thermostatic room temperature control. The inlet temperature is calculated based on the outdoor temperature which, in turn, is used as the temperature setting for the mixing valve.
Block Diagram
The block diagram shows the employed measuring and controlling values.
Controller Input Mask
Input Values
Outdoor Temperature [°C]
The value refers to the weather data being measured. Enter either the weather data outdoor temperature or the 24-h mean outdoor temperature.
Room Temperature Setting [°C]
The value shows how high the room temperature setting is when people are present.
Actual Room Temperature [°C]
The value shows how high the actual average room temperature is.
Flow Rate Settings [l/h]
The value shows the flow rate of the connected convectors. Enter the “Total design flow rate” for the convector. This will be calculated from the convector properties stored in the catalog and the number of existing convectors.
Variable Temperature Setting (Required for Mixing Valve)
Enter the inlet temperature setting for the convector. This value determines the maximum inlet temperature.
Upper Temperature Level (Required for Mixing Valve)
The value shows which components the upper temperature level for the mixing valve is being measured in. Select the appropriate inlet pipe to the mixing valve or the appropriate port on the tank (as shown in the Mixing Valve Controller section).
Lower Temperature Level (Required for Mixing Valve)
The value shows which components the lower temperature level for the mixing valve is being measured in. Select the appropriate pipe to the mixing valve on “Input X“ (as shown in the Mixing Valve Controller section).
Description of Control Parameters
Description
The “description” value enables the user to assign the controller any name or number. Polysun assigns a consecutive number as a standard feature as different controllers are added chronologically in the hydraulic system
Sign of Output
The term “Normal“ means that digital output signals are controlled as intended in the switching logics. The term “Inverted” means that the digital output signals are multiplied by -1.
Heating Loop Activation [°C]
If the outdoor temperature drops below the specified value, the inlet temperature is calculated by means of the outdoor temperature and the inlet temperature setting. If the outdoor temperature exceeds the specified value, the inlet temperature is set to a minimum value.
Cut-in Hysteresis
The pump in the heating circuit cuts in if the actual room temperature lies below the room temperature setting plus the cut-in hysteresis.
Cut-off Hysteresis
The pump in the heating circuit cuts off if the actual room temperature lies above the room temperature setting plus the cut-off hysteresis.
Output values
Status Pump 1
This digital output refers to the pump to be controlled within the heating loop. Select the relevant pump from the list.
Status Switch 2 (Optional)
This digital output is activated just like the Status Pump 1 output. This output enables to control an additional component. For the switching valve “logically one” means that the output “X” on the mixing valve is open. Select the relevant component from the list as required.
Flow Rate Setting
Here, the value indicated for “Flow rate” is transferred to the pump. To this end, select the flow rate of the relevant pump.
This output is only active if the option “Flow rate setting” has been selected in the field “Flow rate controlled” for the pump to be controlled; otherwise the pump settings will have priority over the analogue control outputs. Double click on the pump to check/change settings.
Mixing Valve (Optional)
The required inlet temperature is calculated and the position of the mixing valve is accordingly regulated based on the outdoor temperature and the inlet temperature of the convector. The calculated inlet temperature ranges from a maximum equal to the inlet temperature setting and a minimum equal to the room temperature setting plus 10°C.
Overview of Control-Dependencies
Table: Control-dependencies with or without mixing valve
| Outputs | Parameter | Tip | Inputs | Function |
| Y1: Pump status Y1 = Y2 Y2: Status Switch 2 | Without mixing valve | Adjust pump to – Flow rate setting | X1: outdoor temperature X2: room temperature setting X3: actual room temperature X4: Flow rate setting | Y1=0 if X3 > X2 + cut-off hysteresis [°C] Y1=1 if X3 < X2 + cut-in hysteresis [°C] |
| Y3: Flow rate setting | Y3 = flow rate setting X4 | |||
| Y1: Pump status Y1 = Y2 Y2: Status Switch 2 | With mixing valve | Adjust pump to – flow rate setting Adjust mixing valve to set value | X1: Outdoor temperature X2: Room temperature setting X3: Actual room temperature X4: Flow rate setting X5: Variable temperature setting X6: Upper temperature level X7: Lower temperature level | Y1=0 if X3 > X2 + cut-off hysteresis [°C] Y1=1 if X3 < X2 + cut-in hysteresis [°C] |