Schematic overview
NOT FOR SALE YET - Dehumidifier | Electric heater | freon cooler
Solution description
Advanced temperature and humidity based control system designed specifically for supply-only air handling units. This solution includes a supply fan powered by 400 V and a maximum current of 9.5 A. Paired with cutting-edge frequency inverter, this motor offers exceptional control accuracy and energy efficiency. The controlled AHU is equipped with a 15 kW electric heater, featuring overheating protection. Stepped operation enables precise temperature regulation. Our solution integrates a freon cooler and an AC outdoor unit. Collaborative operation of heater and cooler makes it possible to manage the relative humidity of the supply air. Additionally, this system provides the user with effortless control of the supply filter and air damper, enhancing user experience and convenience.
Additional specifications and description
This solution is designed to monitor and control the air handling unit that is shown in the schematic below:
The air handling unit consists of five parts, which are: supply air damper (1), air filter (2), supply fan (3), DX-cooler (4) and electric heater (5).
Control logic description
The air handling unit operates automatically, relying on sensor readings and predefined protocols for each component.
Supply air damper opens 30 seconds prior to the activation of the supply fan. This is a vital precaution for high airflow units to protect against potential damper damage.
The condition of the air filter is measured using the dual differential pressure transmitter HPD-G-1K0. Readings are passed to the HVAC controller DRPUM (master device). In case the pressure drop on the filter exceeds the setpoint, the user will be notified to perform their maintenance. However, the AHU continues its operation regardless of how clogged the filter is.
The speed of the supply fan can be manually or automatically regulated through the frequency inverter FI-E-44095E2. The HPD-G-1K0 is also used to control fan operation. In the event of mechanical fan issues, such as jamming or bearing breakdown, resulting in no pressure drop, the master device follows specific steps: it deactivates the frequency inverter, closes the air damper, and alerts the user about the error. In automatic mode, the HPD-G-1K0 can be used to maintain determined pressure difference.
To control temperature and humidity simultaneously, the AHU includes an electric air heater and DX-cooler. Both of the parts are controlled by the duct temperature and humidity sensor DSTHM-2, which is installed after the heater. The cooling capacity is adjusted based on relative humidity measurements. If the RH exceeds the setpoint, the air conditioner outdoor unit switches on, supplying the DX-cooler with freon. The relative humidity can be decreased by overcooling the air. However, the resulting air temperature will be too cold for the residents of the served space.
To solve this problem, the AHU utilizes an electric air heater. If the measured temperature drops below the desired threshold, the first step of the electric heater is activated. If the resulting temperature remains lower than the desired one, the operation of the next step will be initiated. As the resulting temperature surpasses the desired value, the steps are deactivated sequentially. To allow the air heater to operate in steps, this solution features Modbus RTU IO module DIO-M-D4. It is also used for the connection of thermal contacts (TK).
The electric air heater features two levels of overheating protection. The first triggers when the casing temperature reaches 60°C, and it restarts automatically. The second level activates at 90°C and requires a manual restart.
To prevent overheating during the AHU shutdown, the electric heater is turned off first, followed by three minutes of fan operation to cool it down. Subsequently, the fan and air damper are deactivated and closed, respectively.
System configuration
This solution includes the network gateway DIG-M-2, granting the user access to the online HVAC platform – SenteraWeb. Connection options include an Ethernet cable or a Wi-Fi network. It allows to remotely monitor data and adjust the settings of the connected HVAC devices via internet. Data logging is also possible.
The air handling unit consists of five parts, which are: supply air damper (1), air filter (2), supply fan (3), DX-cooler (4) and electric heater (5).
Control logic description
The air handling unit operates automatically, relying on sensor readings and predefined protocols for each component.
Supply air damper opens 30 seconds prior to the activation of the supply fan. This is a vital precaution for high airflow units to protect against potential damper damage.
The condition of the air filter is measured using the dual differential pressure transmitter HPD-G-1K0. Readings are passed to the HVAC controller DRPUM (master device). In case the pressure drop on the filter exceeds the setpoint, the user will be notified to perform their maintenance. However, the AHU continues its operation regardless of how clogged the filter is.
The speed of the supply fan can be manually or automatically regulated through the frequency inverter FI-E-44095E2. The HPD-G-1K0 is also used to control fan operation. In the event of mechanical fan issues, such as jamming or bearing breakdown, resulting in no pressure drop, the master device follows specific steps: it deactivates the frequency inverter, closes the air damper, and alerts the user about the error. In automatic mode, the HPD-G-1K0 can be used to maintain determined pressure difference.
To control temperature and humidity simultaneously, the AHU includes an electric air heater and DX-cooler. Both of the parts are controlled by the duct temperature and humidity sensor DSTHM-2, which is installed after the heater. The cooling capacity is adjusted based on relative humidity measurements. If the RH exceeds the setpoint, the air conditioner outdoor unit switches on, supplying the DX-cooler with freon. The relative humidity can be decreased by overcooling the air. However, the resulting air temperature will be too cold for the residents of the served space.
To solve this problem, the AHU utilizes an electric air heater. If the measured temperature drops below the desired threshold, the first step of the electric heater is activated. If the resulting temperature remains lower than the desired one, the operation of the next step will be initiated. As the resulting temperature surpasses the desired value, the steps are deactivated sequentially. To allow the air heater to operate in steps, this solution features Modbus RTU IO module DIO-M-D4. It is also used for the connection of thermal contacts (TK).
The electric air heater features two levels of overheating protection. The first triggers when the casing temperature reaches 60°C, and it restarts automatically. The second level activates at 90°C and requires a manual restart.
To prevent overheating during the AHU shutdown, the electric heater is turned off first, followed by three minutes of fan operation to cool it down. Subsequently, the fan and air damper are deactivated and closed, respectively.
System configuration
This solution includes the network gateway DIG-M-2, granting the user access to the online HVAC platform – SenteraWeb. Connection options include an Ethernet cable or a Wi-Fi network. It allows to remotely monitor data and adjust the settings of the connected HVAC devices via internet. Data logging is also possible.
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