Schematic overview
NOT FOR SALE YET - Temperature-based control | AC fans | recirculation
Solution description
Cutting-edge temperature-based control system for recirculation air handling unit. The system features two AC fans equipped with frequency inverters, designed to operate on a 3-phase 400 V power supply, with a power rating of 4 kW and a maximum current of 9,5 A. The AHU incorporates a recirculation chamber with an actuator-controlled damper. It also includes a water heater complete with a pump and a valve. The heater is equipped with frost protection mechanisms, ensuring reliable operation even in freezing conditions. To provide effective cooling, the AHU integrates a water cooler with a chiller and a responsive 3-way valve. To maintain optimal system performance, our solution includes filter clogging control and fan operation control through pressure sensors. Additionally, our system offers comprehensive control over the supply and exhaust dampers, enabling precise airflow management and ventilation control.
Additional specifications and description
This solution is designed to monitor and control air handling unit that is shown on schematic below:
Air handling unit consists of eight parts, which are: supply (1), exhaust (7) and recirculation (2) air dampers; supply air filter (3); supply (4) and exhaust (8) fans; air heater (5) and air cooler (6).
Control logic description
This solution is designed to ensure fully automatic operation of the AHU. The operating mode is determined by sensor readings. The HVAC controller DRPUM has built-in predefined logics for different AHU parts.
To ensure optimal performance and prevent potential damage to the air dampers, the supply and exhaust air dampers open 30 seconds prior to the activation of the supply and exhaust fans. This is particularly crucial for high air flow AHUs.
The condition of the air filter is measured via a differential pressure transmitter HPS-M-1K0-2. The measurements are transferred to DRPUM (master device). If the pressure drop on the filter exceeds the setpoint, the user will receive a notification to perform maintenance. However, the AHU continues its operation regardless of how clogged the filter is.
The supply and exhaust fan speed can be controlled either manually or automatically via frequency inverters FI-E-44095E2. Dual differential pressure transmitter HPD-G-1K0 is also used to control fan operation. In case of mechanical failure (jamming, bearing breakdown), there will be no pressure drop and the master device will take the following steps: switch off frequency inverters, close air dampers, and inform the user about the error. In automatic mode HPD-G-1K0 can be used to maintain a specific pressure difference.
Additionally, this solution includes a recirculation system, consisting of three actuator-controlled air dampers: supply, exhaust and recirculation. Users can choose from two different control options. The first option utilizes duct temperature and humidity sensor DSTHM-2, which is installed inside the mixing chamber. The position of dampers is defined by the desired air temperature in the mixing chamber. The second option implies manual input of the required damper positions. In this mode, DSTHM-2 monitors the resulting temperature. The recirculation system can be utilized both during cold and warm periods of the year and can be easily deactivated by closing the recirculation damper.
The air heater operation is regulated using a duct temperature and humidity sensor DSTHM-2. If the measured temperature is higher than the desired one, the 3-way valve starts to close, reducing the amount of hot water supplied to the air heater. Conversely, if the measured temperature falls below the desired value, the 3-way valve gradually opens. The pump maintains a constant speed at all time to ensure hydraulic regime.
The air heater has two types of frost protection: air and water. Air frost protection is provided with a special relay - frost protection thermostat. It is placed directly after the heater and used to measure temperature. If the measured value drops below adjustable setpoint, the following sequence occurs:
Air handling unit consists of eight parts, which are: supply (1), exhaust (7) and recirculation (2) air dampers; supply air filter (3); supply (4) and exhaust (8) fans; air heater (5) and air cooler (6).
Control logic description
This solution is designed to ensure fully automatic operation of the AHU. The operating mode is determined by sensor readings. The HVAC controller DRPUM has built-in predefined logics for different AHU parts.
To ensure optimal performance and prevent potential damage to the air dampers, the supply and exhaust air dampers open 30 seconds prior to the activation of the supply and exhaust fans. This is particularly crucial for high air flow AHUs.
The condition of the air filter is measured via a differential pressure transmitter HPS-M-1K0-2. The measurements are transferred to DRPUM (master device). If the pressure drop on the filter exceeds the setpoint, the user will receive a notification to perform maintenance. However, the AHU continues its operation regardless of how clogged the filter is.
The supply and exhaust fan speed can be controlled either manually or automatically via frequency inverters FI-E-44095E2. Dual differential pressure transmitter HPD-G-1K0 is also used to control fan operation. In case of mechanical failure (jamming, bearing breakdown), there will be no pressure drop and the master device will take the following steps: switch off frequency inverters, close air dampers, and inform the user about the error. In automatic mode HPD-G-1K0 can be used to maintain a specific pressure difference.
Additionally, this solution includes a recirculation system, consisting of three actuator-controlled air dampers: supply, exhaust and recirculation. Users can choose from two different control options. The first option utilizes duct temperature and humidity sensor DSTHM-2, which is installed inside the mixing chamber. The position of dampers is defined by the desired air temperature in the mixing chamber. The second option implies manual input of the required damper positions. In this mode, DSTHM-2 monitors the resulting temperature. The recirculation system can be utilized both during cold and warm periods of the year and can be easily deactivated by closing the recirculation damper.
The air heater operation is regulated using a duct temperature and humidity sensor DSTHM-2. If the measured temperature is higher than the desired one, the 3-way valve starts to close, reducing the amount of hot water supplied to the air heater. Conversely, if the measured temperature falls below the desired value, the 3-way valve gradually opens. The pump maintains a constant speed at all time to ensure hydraulic regime.
The air heater has two types of frost protection: air and water. Air frost protection is provided with a special relay - frost protection thermostat. It is placed directly after the heater and used to measure temperature. If the measured value drops below adjustable setpoint, the following sequence occurs:
- Both supply and exhaust fans stop, air dampers close;
- The 3-way valve fully opens;
- When the air temperature after the heater exceeds the setpoint, dampers and fans resume their normal operation.
Water frost protection is ensured by using a temperature sensor for fluid pipes DTP-M. It should be installed on the return water pipe at the exit from the air heater. If the measured water temperature drops below 25°C (this setpoint can be changed), the following scenario will occur:
- Both supply and exhaust fans stop, air dampers close;
- The 3-way valve fully opens;
- When the water temperature after heater surpasses 25°C, dampers and fans will resume their normal operation.
The air cooler operation relies on measurements given by the room temperature and humidity sensor RSTHM-2. If the actual temperature is higher than the desired value, the 3-way valve opens to supply the air cooler with cold water. The valve position depends on the temperature differential – the hotter the room, the wider the valve opens. Duct temperature sensors are not used to control the air cooler due to the fact that air can warm up while passing through the fan and ducts.
System configuration
This solution includes a network gateway DIG-M-2. It provides the user with access to the online HVAC platform – SenteraWeb. The connection can be established via an Ethernet cable or a Wi-Fi network. It allows remote monitoring of data and adjustment of settings for the connected HVAC devices via the internet. Data logging is also supported.
System configuration
This solution includes a network gateway DIG-M-2. It provides the user with access to the online HVAC platform – SenteraWeb. The connection can be established via an Ethernet cable or a Wi-Fi network. It allows remote monitoring of data and adjustment of settings for the connected HVAC devices via the internet. Data logging is also supported.
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