6 Minute Read
| Overview
The SmartStat Heat Pump Unit (HPU) is profile introduced by 75F to provide zone level control using the SmartStat device. Heat pump units are used in buildings in regions that could experience extreme weather and require more heating during times. The heat pump unit is capable enough to provide necessary heating and cooling to the space, efficiently conserving energy. The heat pump unit consists of the compressor with refrigerant, a reversing valve, a fan, and Auxiliary heating equipment that provides the required conditioning.
| How it Works
The 75F SmartStat Heat Pump Unit (HPU) is a unique profile, that provides both heating and cooling conditioning.
Based on whether the unit is in the heating operation or cooling operation the reversing valve is set to reverse the direction of the flow of the refrigerant switching the condenser and the evaporator coil of the system to provide the necessary conditioning.
The reheat capability is enabled with the auxiliary heating stages which only gets triggered during the Auto and Heat Only mode when the compressor-provided heat is not sufficient (where additional heat is required).
The SmartStat HPU allows the choice between fully modulating and staged equipment control. The possible equipment configurations include:
- 2- Stage Compressor Control
- 1- Stage Auxiliary heating control
- 2- Stage Fan Speed Control
- Reversing Valve Control (Heatpump Changeover Relay; Type O or Type B)
- 2 Thermistor inputs
| Application of Deadband and Hysteresis
The diagrams below show the application of the Deadband and Hysteresis Band and their role:
| Wiring Diagram
| Configuration
- Select the Smartstat option from the device screen.
- Select Heat Pump Unit (HPU) from the module type.
The pairing options are displayed on the screen which provide the steps to successfully pair the device.
- Select the displayed Bluetooth address.
- Enter the corresponding PIN from the device.
- Click Pair to start the pairing
You can see the configuration screen for the Heat Pump Unit (HPU) with the following options available for configuration.
| Configuration Parameters
Once the SmartStat is paired as a Heat Pump Unit (HPU), you will need to enable the required configuration parameters below, which define the device's physical characteristics.
| Parameters | Usage/Purpose |
| Compressor Stage 1 | Used to connect and control both heating and cooling stages as per zone requirements. |
| Compressor Stage 2 | Used to connect and control both heating and cooling stages as per zone requirements. |
| Fan Low Speed | Used to connect a fan stage control. |
| Auxilliary Heating Stage 1 | Used to provide additional heating as per zone requirements. |
| Fan High Speed | Used to connect a fan stage control. |
| Heatpump Changeover | Indoor or Outdoor Unit reversing valve which is used for a cooling or heating loop output as per zone requirements. |
| Airflow Temperature Sensor (Th1) | Used when an airflow temperature sensor is provisioned for the system. |
| Use External 10k Temp Sensor | Used when an external 10K temperature sensor is provisioned for the system. |
| Enable Occupancy Sensing | Used for an occupancy-based setpoint control. |
Test Signal
This is used for troubleshooting and testing the equipment if the configuration and the field setup are in sync, and the device is communicating properly with the controlled equipment. Also at any point, you can override the value of the output the algorithm decides.
We can use the test signal for relays to turn them on or for analog out to ramp up and see if the equipment works according to commands from the device.
Test Signal Time Out
once enabled it will be active for an hour if the screen is not changed, after an hour of no interaction on the screen. zone screen displays and the test signal will be OFF.
If the screen changes from the test signal configuration screen it will be timed out in one minute (time for the algorithm to run next).
- Enable the required parameters as below.
- Click Set to confirm the parameters.
| Post Configuration
The zone paired with the HPU profile is displayed in the CCU as below.
Below are widgets configured in the heatmap pages in the portals.
The user is also provided with profile reconfiguration options from the Internal portal as shown below, with all the features and capabilities that were available in CCU as explained in the above sections.
| Modes & Operations
As in the other SmartStat profiles, the HPU profile as well supports the following fan and conditioning modes.
Fan Modes
- Off
- Auto
- Fan Low Current Occupied Period
- Fan Low Occupied Period
- Fan Low All Times
- Fan High Current Occupied Period
- Fan High Occupied Period
- Fan High All Time
Based on the fan stages configured in the configuration window, the fan stages are made available in CCU and the portal for selection as user intents.
And when a change is made, it would translate to the following in the CCU.
- Auto------ Auto
- Low------Fan Low Current Occupied Period
- High-------Fan High Current Occupied Period
Conditioning Modes
- Off
- Auto
- Cool Only
- Heat Only
The conditioning modes are also made available in CCU and the portal for selection as user intents.
| Controls & Triggers Strategy
| Controls | Trigger Strategy |
| Compressor stages | Compressor stages trigger during both heating and cooling based on the zone demands. When the zone demands cooling the compressor stages trigger is determined based on the cooling loop output. And when the zone demands heating, the compressor stages trigger is determined based on the Heating loop output. |
| Auxiliary Heating Stage |
Auxiliary heating stage is triggered based on the below scenario:
|
| Fan Stages |
Fan stages trigger based on the fan loop output which is a result of cooling loop and heating loop outputs, during cooling and heating compressor operation respectively.
|
| Heatpump Changeover |
A relay mapped to the changeover valve is activated when the zone is demanding heating, during heating operation, and there is a heating loop output, and the relay is deactivated otherwise. A relay mapped to the changeover valve is activated when the zone is demanding cooling, during cooling operation, and there is a cooling loop output, and the relay is deactivated otherwise. |
| Equip Graphics for Smartstat Heat Pump Unit (HPU)
Equipment graphics is available for all the terminal profiles. It provides a graphical representation of system-level equipment and enables monitoring of key point parameters associated with terminal profiles.
The highlighted list of points is predefined for visualization alongside the graphic for the respective profile.
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