Systems with variable air flow vav valve. VAV ventilation systems systemair. More than a split
The main purposes of this system are: reducing operating costs and compensating for filter contamination.
Using a differential pressure sensor, which is installed on the controller board, the automation recognizes the pressure in the channel and automatically equalizes it by increasing or decreasing the fan speed. The supply and exhaust fans operate synchronously.
Compensation for filter contamination
When operating a ventilation system, the filters inevitably become dirty, the resistance of the ventilation network increases and the volume of air supplied to the premises decreases. The VAV system will allow you to maintain a constant air flow throughout the entire life of the filters.
- The VAV system is most relevant in systems with a high level of air purification, where filter contamination leads to a noticeable decrease in the volume of supplied air.
Reduced operating costs
The VAV system can significantly reduce operating costs, this is especially noticeable in supply ventilation systems, which have high energy consumption. Savings are achieved by completely or partially turning off the ventilation of individual rooms.
- Example: you can turn off the living room at night.
At calculation of the ventilation system are guided by different standards of air consumption per person.
Typically, in an apartment or house, all rooms are ventilated simultaneously; the air flow for each room is calculated based on the area and purpose.
What to do if at the moment is there anyone in the room?
You can install valves and close them, but then the entire volume of air will be distributed throughout the remaining rooms, but this will lead to increased noise and waste of air, the precious kilowatts were spent heating it.
You can reduce the power of the ventilation unit, but this will also reduce the volume of air supplied to all rooms, and where users are present there will be “not enough air”.
The best solution is to supply air only to those rooms where there are users. And the power of the ventilation unit must be regulated itself, according to the required air flow.
This is exactly what a VAV ventilation system allows you to do.
VAV systems pay for themselves quite quickly, especially in air handling units, but most importantly, they can significantly reduce operating costs.
- Example: Apartment 100m2 with and without VAV system.
The volume of air supplied to the room is controlled by electric valves.
An important condition for the construction of a VAV system is the organization of the minimum supplied air volume. The reason for this condition lies in the inability to control air flow below a certain minimum level.
This can be solved in three ways:
- in a single room, ventilation is organized without the possibility of regulation and with an air exchange volume equal to or greater than the required minimum air flow in the VAV system.
- A minimum amount of air is supplied to all rooms with the valves turned off or closed. The total of this amount must be equal to or greater than the required minimum air flow in the VAV system.
- The first and second options together.
Control from a household switch:
To do this, you will need a household switch and a valve with a return spring. Switching on will lead to the full opening of the valve, and the room will be ventilated in full. When switched off, the return spring closes the valve.
Damper switch/switch.
- Equipment: For each serviced room you will need one valve and one switch.
- Operation: If necessary, the user turns the room ventilation on and off using a household switch.
- Pros: The simplest and budget option VAV systems. Household switches always fits the design.
- Cons: User participation in regulation. Low efficiency due to on-off regulation.
- Advice: It is recommended to install the switch at the entrance to the serviced room, at +900mm, next to or in the light switch block.
The minimum required volume of air is always supplied to room No. 1; it cannot be turned off; room No. 2 can be turned on and off.
The minimum required volume of air is distributed to all rooms, since the valves are not completely closed and a minimum amount of air passes through them. The entire room can be turned on and off.
Control from a rotary regulator:
This will require a rotary regulator and a proportional valve. This valve can open, regulating the volume of supplied air in the range from 0 to 100%, the required degree of opening is set by the regulator.
Circular regulator 0-10V
- Equipment: for each room served, one valve with 0...10V control and one 0...10V regulator will be required.
- Operation: If necessary, the user selects the required level of room ventilation on the regulator.
- Pros: More precise regulation of the amount of air supplied.
- Cons: User participation in regulation. Appearance regulators do not always fit the design.
- Advice: It is recommended to install the regulator at the entrance to the serviced room, at +1500mm, above the light switch block.
The minimum required volume of air is always supplied to room No. 1; it cannot be turned off; room No. 2 can be turned on and off. In room No. 2 you can smoothly regulate the volume of supplied air.
Small opening (valve 25% open) Medium opening (valve 65% open)
The minimum required volume of air is distributed to all rooms, since the valves are not completely closed and a minimum amount of air passes through them. The entire room can be turned on and off. In each room you can smoothly regulate the volume of supplied air.
Presence sensor control:
This will require a presence sensor and a valve with a return spring. When registering in the user’s room, the presence sensor opens the valve and the room is ventilated in full. When there is no user, the return spring closes the valve.
Motion sensor
- Equipment: For each serviced room you will need one valve and one presence sensor.
- Operation: The user enters the room - ventilation of the room begins.
- Pros: The user does not participate in the regulation of ventilation zones. It is impossible to forget to turn the room ventilation on or off. Many occupancy sensor options.
- Cons: Low efficiency due to on-off regulation. The appearance of presence sensors does not always suit the design.
- Advice: Use high-quality presence sensors with a built-in time relay for the correct operation of the VAV system.
The minimum required volume of air is always supplied to room No. 1; it cannot be turned off. When the user registers, ventilation of room No. 2 begins
The minimum required volume of air is distributed to all rooms, since the valves are not completely closed and a minimum amount of air passes through them. When a user registers in any of the rooms, ventilation of this room begins.
CO2 sensor control:
This requires a CO2 sensor with a 0...10V signal and a proportional valve with 0...10V control.
When the CO2 level in the room is detected, the sensor begins to open the valve in accordance with the recorded CO2 level.
When the CO2 level decreases, the sensor begins to close the valve, and the valve can close either completely or to a position at which the required minimum flow will be maintained.
Wall or duct CO2 sensor
- Example: For each room served, one proportional valve with 0...10V control and one CO2 sensor with a 0...10V signal will be required.
- Operation: The user enters the room, and if the CO2 level is exceeded, ventilation of the room begins.
- Pros: The most energy efficient option. The user does not participate in the regulation of ventilation zones. It is impossible to forget to turn the room ventilation on or off. The system starts ventilation of the room only when it is really needed. The system most accurately regulates the volume of air supplied to the room.
- Cons: The appearance of CO2 sensors does not always match the design.
- Advice: Use high-quality CO2 sensors for correct operation. Duct CO2 sensor can be used in supply and exhaust systems ventilation, if the serviced room has both supply and exhaust.
The main reason why room ventilation is required is if the CO2 level is too high.
In the process of life, a person exhales a significant amount of air with a high level of CO2, and being in an unventilated room, the level of CO2 in the air inevitably increases, this is what determines when they say that there is “little air.”
It is best to supply air into the room when the CO2 level exceeds 600-800 ppm.
Based on this air quality parameter, you can create the most energy efficient ventilation system.
The minimum required volume of air is distributed to all rooms, since the valves are not completely closed and a minimum amount of air passes through them. When an increase in CO2 content is detected in any room, ventilation of that room begins. The degree of opening and the volume of air supplied depends on the level of excess CO2 content.
Management of the Smart Home system:
This will require a system Smart home"and any type of valves. Any type of sensors can be connected to the Smart Home system.
Air distribution can be controlled either through sensors using a control program, or by the user from a central control panel or a phone application.
Smart home panel
- Example: The system operates using a CO2 sensor and periodically ventilates the premises, even in the absence of users. The user can forcefully turn on ventilation in any room, as well as set the amount of air supplied.
- Operation: Any control options supported.
- Pros: The most energy efficient option. Possibility of precise programming of the weekly timer.
- Cons: Price.
- Advice: Install and configure by qualified specialists.
Variable Air Volume - variable air flow
SYSTEMAGROUP specialists have implemented more than one project using Systemair VAV ventilation and air conditioning systems, both at the design and installation stage and in the modernization of existing systems.
Advantages of VAV - variable air flow systems over CAV - constant air flow systems:
- Individual comfort of each room- organization of air supply is carried out according to demand from a certain external factor or their sum and priority: temperature t, humidity, CO2, movement.
- Energy Saving- maximum energy efficiency, allows you to save up to 70% of electricity consumption.
- Increases equipment lifespan
- Low noise level of system operation
Let's look at three examples of the objects we have implemented, the layout of VAV systems from advanced to simple.
In all three examples, air handling units with recovery are used. The ventilation system control mode is carried out by maintaining the temperature t of the exhaust air (maintaining room temperature). The ventilation system controller itself sets the temperature t supply air(tmin and tmax).
1. Example
The task set by the Customer is to individually maintain accurate and continuous control of humidity and temperature t in each of six residential premises: four bedrooms, a living room, a dining room.
In this project, it was necessary to regulate six zones; the operating principle of the system was implemented on VAV variable air flow regulators OPTIMA and an optimizer controller.
The air flow of a given VAV system is independent of the pressure in that system.
- VAV variable flow controllers receive a control signal (0/2-10V) from humidity and temperature sensors t installed in the premises - Vx m3/h is required.
- The moving air stream creates a pressure difference, which is measured using a pitot tube
- The actual air flow value m3/h, obtained using a differential pressure sensor, is sent to the variable flow controller controller
- The controller compares the actual air flow m3/h. and the required value, in the presence of deviations, sends a correction signal to the electric drive, which adjusts the valve cross-section until the required air flow m3/h. will not be achieved
- The optimizer controller receives signals via the MP-bus network from all VAV controllers and adjusts the operation of the fans.
- Topvex TR_EL - vertical air handling unit with rotary heat exchanger and electric heater
- AIAS COMBOX MODULE - controller optimizer for VAV variable flow regulators
- CO2RT Wall mounting 0-2000 ppm - CO2 level, humidity and temperature converters
- OPTIMA-R-BLC1 - variable flow regulators
- Mitsubishi Electric SUZ-KA_ inverter - compressor-condensing unit (KKB)
- DXRE - freon cooler
- PAC-IF012B-E - KKB controller
- Carel compactSteam is an isothermal humidifier.
2. Example
The task set by the Customer is to maintain accurate and continuous control of CO2 concentration and temperature t in two gyms.
In this project, it was necessary to regulate two zones, the operating principle is implemented according to the scheme - The air flow of a given VAV system depends on static pressure Pa in this system.
- Electric actuators of air valves receive a control signal (0/2-10V) from sensors of CO2 concentration and temperature t installed in sports halls
- The air valve, changing the cross-section, supplies the required air flow m3/h.
- The moving air flow creates a pressure difference Pa, which is measured by differential pressure sensors
- Differential pressure sensors send a signal to the controller air handling unit, which in turn adjusts the operation of the fans depending on the current demand for air flow m3/h.
Equipment installed at the site:
- Topvex FR_HWL - horizontal air handling unit with rotary heat exchanger and water heater
- VAV Duct pressure control - differential pressure sensors
- Belimo LF 24-SR - electric drives 0-10V controlled by CO2 level converters
- DXRE - freon cooler
- PAC-IF013B-E - KKB controller.
3. Example
The task set by the Customer was to maintain accurate and continuous temperature control in the office premises.
In this project it was necessary to ensure the temperature of a single office space(call center). The operating principle of the system is implemented according to a scheme controlled directly by the Corrigo ventilation system controller. The Corrigo controller settings allow you to change the air flow m3/h. depending on the temperature deviation t in the room.
Equipment installed at the site:
- Topvex FC_EL - suspended air handling unit with recuperator and electric heater
- DXRE - freon cooler
- Mitsubishi Electric PUHZ-ZRP_YKA inverter - compressor-condensing unit (KKB)
- PAC-IF013B-E - KKB controller
The health, well-being of people and the efficiency of their work directly depend on the indoor climate. BELIMO solutions for rooms and systems - a complete range of products for energy-saving climate control in zones and separate rooms buildings for industrial and civil purposes - confirm their advantages in a huge number of projects around the world.
VAV systems are:
individual regulation of air parameters in individual rooms;
the ability to use motion sensors, CO2 sensors, time relays and manual controllers to change air flow;
reduction in costs for the production and installation of a network of air ducts, and reduction in the cost of equipment for air preparation;
reduction of electricity consumption; simplification of the process of starting and setting up the ventilation network;
possibility of continuous monitoring of the amount of air in individual branches of the network air channels;
possibility of centralized control of air flow in the installation;
the possibility of re-equipping the ventilation system in relation to new conditions.
VAV - compact - effective management indoor climate control with one device
Electric drive, controller and sensor in one device - VAV-compact provides economical way control of variable and constant air flows in office buildings, hotels, hospitals, etc. Special rotary electric actuators with torques of 5, 10 and 20 Nm and linear electric actuators with 150 Nm can be installed on VAV/CAV valves in a wide range of sizes. VAV compact controllers are controlled as traditional way, and via the BELIMO MP-bus network. MP models can be integrated into systems over high level– together with one sensor per device - either through a DDC controller with an integrated MP interface, or through a gateway. The fans are connected via the Mp-bus network to the Fan Optimizer, which greatly simplifies the process of optimizing energy consumption depending on needs
VAV - universal - flexibility in case of challenging environments
The range of ready-to-connect VAV-universal devices includes rotary and security electric drives, as well as regulators with dynamic and static pressure sensors. These devices can be customized to the exact requirements of specific industrial, commercial and public buildings. Digital self-adjusting VRP-M regulators interact with fast-acting electric drives in laboratories or industrial environments with a polluted atmosphere, providing instantaneous fresh air. Depending on the specific choice, the automation system can be integrated into a higher-level network and equipped - directly or via an MP-bus network - with the BELIMO fan optimizer, which allows reducing up to 50% of the energy consumed by the fan
The operating principle of VAV ventilation is based on maintaining constant air pressure in the central air duct. All fresh air consumers (usually called zones) are connected to the central air duct through a motorized valve. By controlling the electric drive, we can open or close the valve, which means open, close or regulate the volume of fresh air entering the zone. A zone can be one room, several rooms, a floor, several floors, etc.
When opening the fresh air supply to the room, the pressure in the central air duct supplies, ventilation unit it “feels” and begins to increase the fan speed (and therefore increasing the volume of fresh air) until it reaches set pressure. Conversely, when a zone is closed, the pressure in the central air duct increases and the ventilation unit reduces the volume of fresh air supplied. When opening/closing/regulating a zone, no changes in the volume of supplied air occur in other zones.
What is all this for? To save operating resources, costs for heating fresh air, and increase the service life of ventilation equipment.
In this section we will look at how to control VAV valves.
The easiest way to control is discrete(zones are either open or closed). This is achieved by installing an electric drive with a voltage of 220 Volts and discrete control on the valve. Control is carried out by applying/removing voltage from the control contact of the electric drive. As a rule, turning a zone on/off is done using the key of a regular switch. The advantage of this type of control is its low cost. The disadvantage is the inconvenience of operation - you need to manually turn on/off the air supply and remember this all the time (did I turn off the air, iron, light, kettle, etc.)
The second control method is smooth, from dimmer. This is achieved by installing an electric drive with a voltage of 24 Volts and smooth control on the valve. Control is performed by rotating the dimmer key in one direction or another. The advantage of this type of control is also its low cost. The disadvantage is, again, the inconvenience of operation - you need to manually turn on/off/adjust the air supply and remember this all the time. In addition, dimmers do not always match the design of light switches, although they are often installed next to each other.
The third control method is from the ventilation unit remote control. This is achieved by installing an electric drive with a voltage of 24 Volts and smooth control on the valve. Control is carried out by regulating the volume of fresh air supplied from the ventilation unit remote control or automatically according to a user-specified scenario (timer). The advantage of this type of control is the possibility of more flexible control of fresh air flows and ease of operation. The disadvantage is the installation cost of this type of VAV valve control, but as they say, “beauty requires sacrifice.”
 | In order not to constantly have to manage the valves, the operation of the VAV valves is adjusted depending on the concentration of the carbon dioxide (CO2) level. But today, normally functioning CO2 sensors are quite expensive, so scripts are used to make using VAV ventilation more convenient. A scenario is a pre-programmed algorithm for VAV ventilation operation. In the picture, the “Day 2” scenario is activated. The names of the scenarios are conventional and help you remember what this scenario is intended for. For example, the “Guests” scenario can be configured to supply maximum fresh air to the living room, and the “Night” scenario to supply fresh air only to the bedrooms. Each scenario can be edited and customized to suit your requirements. |
The TRD remote is universal device and can control VAV valves from almost any ventilation unit that supports the VAV function. Small videos posted on YouTube will help you better understand the principle of operation of the VAV system and its control:
The approximate cost of a VAV ventilation device can be found out by calling our phones, the final cost is only after calling an engineer for an inspection and clarifying all the nuances, subtleties and your wishes.
VAV system is a ventilation system with variable flow air (Variable Air Volume). This is a cost-effective way to create an energy-efficient ventilation system that allows you to save energy without compromising your comfort level. Modern VAV systems allow them to quickly pay for themselves during operation due to a significant reduction in consumed energy resources.
The main advantage of VAV systems is significant savings energy, especially relevant for ventilation systems with an electric heater: users have the opportunity to turn the ventilation on and off in any room in the same way as turning the light on and off. And the use of valves with proportional electric drives will make control even more convenient, allowing users to smoothly adjust the volume of supplied air. You can also change the air volume based on a signal from a presence sensor (analogous to the Smart Eye system used in household split systems), temperature, humidity, CO 2 concentration sensors and others - all this will allow you to automate energy saving management.
Example: You can turn off the living room at night.
As a rule, in an apartment/house, ventilation of all rooms occurs simultaneously, based on the calculated volume for each room (the area of the room, purpose, number of people is taken into account). But a situation often arises when there is no one in some rooms. You can install control valves and shut them off, which will lead to the redistribution of the entire air volume to the remaining rooms. But there will be a problem with an increase in air flow, and consequently, an increase in noise level and waste of air, for heating of which kilowatts of electricity will be spent. It is also possible to reduce the supply air setpoint, but this will result in a shortage of air in rooms with people.
That's why best solution- use a zone ventilation system (VAV system). It allows you to supply the required volume of air to those rooms where people are currently located. A power air handling unit will be regulated independently, depending on the load at any given time.
The payback period for a zone ventilation system is very short, since the use of a VAV system can significantly reduce operating costs.
For example:
Family of 4, with two children. Mom doesn't work. One child goes to school / kindergarten. The second one is still small and stays at home with his mother.
Ventilation without the use of a VAV system
| Room | Schedule of people present in the premises, number of people |
Air flow | |||||||||
| Total, m 3 /hour | 6 00 - 8 00 | 9 00 - 10 00 | 10 00 - 12 00 | 12 00 - 15 00 | 15 00 - 19 00 | 19 00 - 21 00 | 21 00 - 23 00 | 23 00 - 6 00 | |||
| Living room* | 4 | 45 | 180 | 3 | 2 | 0 | 1 | 1 | 4 | 3 | 0 |
| Bedroom | 2 | 45 | 90 | 0 | 0 | 0 | 0 | 0 | 0 |
0 |
2 |
| Children's | 2 | 45 | 90 | 1 | 0 | 0 | 1 | 2 | 0 | 1 | 2 |
| Cabinet | 1 | 45 | 45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Performance: | 100% | 100% | 100% | 100% | 100% | 100% | 100% | 100% | 100% | ||
| Air consumption, m 3 /hour | 405 | 405 | 405 | 405 | 405 | 405 | 405 | 405 | 405 | ||
| 5020 | 5020 | 5020 | 5020 | 5020 | 5020 | 5020 | 5020 | 5020 | |||
| 121 | |||||||||||
Ventilation using a VAV system
| Room | Schedule of people present in the premises, number of people | Air flow | Schedule of people present in the premises | ||||||||
| Norm for 1 person, m 3 /hour*** | Total, m 3 /hour | 6 00 - 8 00 | 9 00 - 10 00 | 10 00 - 12 00 | 12 00 - 15 00 | 15 00 - 19 00 | 19 00 - 21 00 | 21 00 - 23 00 | 23 00 - 6 00 | ||
| Living room* | 4 | 45 | 180 | 3 | 2 | 2 | 1 | 1 | 4 | 3 | 0 |
| Bedroom | 2 | 45 | 90 | 0 | 0 | 0 | 0 | 0 | 2 | ||
| Children's | 2 | 45 | 90 | 1 | 0 | 0 | 1 | 2 | 0 | 1 | 2 |
| Cabinet | 1 | 45 | 45 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Performance: | 100% | 44,44% | 22,22% | 22,22% | 22,22% | 33,33% | 44,44% | 44,44% | 44,44% | ||
| Air flow | 405 | 180 | 90 | 90 | 90 | 135 | 180 | 180 | 180 | ||
| Required heating power, W** | 5020 | 2231 | 1116 | 1116 | 1116 | 1673 | 2231 | 2231 | 2231 | ||
| Total energy consumption per day, kW*hour | 44 | ||||||||||
* air flow in the living room takes into account the compensation of natural kitchen and bathroom hoods to remove odors, taking into account the time when the family gathers for breakfast and dinner
** power consumption is given for winter period, calculated outside temperature-15 °C, air temperature supplied to the premises +22 °C
As a result of using the VAV system, we received significant savings and a 3-fold reduction in air heating costs, while maintaining the level of comfort and the volume of air supplied to the areas where people are staying.
How the VAV system works
A typical VAV system consists of the following components:
- Ventilation unit with smoothly variable performance. It must use an electronically commutated (inverter) fan or regular fan, controlled by a speed controller (electronic autotransformer), which allows you to smoothly change the fan rotation speed.
- Air distribution chamber, in which a constant (set) pressure is maintained. Air ducts from all serviced rooms are connected to this chamber.
- Differential pressure sensor, which is located near the distribution chamber. The sensor uses a thin tube to measure the pressure inside the chamber and transmits this information to the ventilation unit.
- Motorized air valves(VAV valves) controlled from switches or regulators (not shown in the diagram).
Let's figure out how it all works. Let's assume that at the beginning all air valves are fully open. If one of the valves closes during operation, the pressure in the air distribution chamber begins to increase. This change is recorded by a sensor, and the automatic system of the air handling unit reduces the fan rotation speed just enough so that the pressure in the chamber returns to its previous level ( transition process takes no more than one minute). Thus, the automation system constantly monitors the pressure level in the chamber and, if it deviates in one direction or another from the set value, changes the fan rotation speed so that the pressure returns to normal. Since the pressure in the chamber, and therefore at the inlet of each air duct, is constant, the volume of air entering the premises will be determined only by the angle of rotation of the damper of the corresponding valve. The illustration shows a VAV system serving only 3 rooms, but there can be any number of these rooms.
All equipment used to build a VAV system can be divided into two parts: a ventilation unit with a pressure sensor and an air distribution network with adjustable zones. Both parts of the VAV system can operate independently of each other: the ventilation unit, using a sensor, maintains a set pressure in the air distribution chamber, and the user, using switches, can close and open valves in all zones at his discretion. Since the pressure in the chamber is constant, the air flow in each room will depend only on the position of the valve damper in this room, and will not depend on the air flow in other rooms.
Types of zone ventilation systems
According to the type of control, VAV systems can be:
1. With local control and discrete drives(valves have only two positions - open and closed, controlled by switches).
2. With local control and SV-02 modules, which control proportional drives. Regulators are connected to these modules, allowing you to smoothly change the air flow in each zone.
3. With centralized control and JL201 modules, which control proportional drives. In this case, the air flow can be regulated locally (using regulators or sensors), centrally from a remote control or using a CO 2 sensor. Accordingly, the console and JL201 modules must be connected by a data cable.
VAV system with discrete valve control
This is the simplest and most inexpensive type of VAV system.
The system shown in the illustration consists of a Breezart 550 Lux air handling unit, a JL201DPR pressure sensor and several air valves with discrete (that is, having only two positions: open or closed) electric actuators. The drives are controlled using conventional switches, which are installed in the serviced premises and allow you to open or close the valve by supplying or removing power from it (the valves have an operating voltage of 220V). To connect the pressure sensor to the ventilation unit, you need a crossover module RSCON and a 24V power supply. The length of the tube from the JL201DPR module to the measuring point should not exceed 2 meters. The valves can be controlled not only manually, but also automatically from overhead lighting or a motion sensor with a turn-off delay and a 220V relay output (such sensors are used to control the external lighting of cottages).
To reduce the cost of the system and the space it takes up, in the example given, an air distribution chamber is not used; constant pressure is maintained in the channel. As noted above, in this case all air ducts must be routed from one point.
System Description:
- Room No. 1 – control from the switch. Here, as near valve No. 5, a balancing throttle valve is installed, which allows you to adjust the air flow specified by the project for a given room when the VAV valve is open. A balancing valve is only needed when the drive's mechanical rotation angle limiters cannot achieve acceptable air flow accuracy.
- Rooms No. 2 and 3 – two rooms are combined into one zone, controlled by a switch.
- The valve in room No. 4 does not have an electric drive. It is balanced at the commissioning stage for a given air flow (at least 10% of maximum flow air) and ensures normal operation of the ventilation unit when all other valves are closed.
- Room No. 5 – control from a motion sensor. The valve opens automatically when human movement is detected in the room. Shutdown occurs automatically after a specified time (usually set in the range of 1–15 minutes) after the last sensor activation.
A zone with a fixed flow rate (room No. 4) can be abandoned if you adjust the extreme position of one drive or the position of the damper in such a way that in the “closed” state the minimum amount of air required for normal operation of the ventilation unit enters the room. It is advisable to use only one zone for this, since if there are several slightly open dampers and the ventilation is turned off, voices and other noises can spread between rooms through the air ducts (with ventilation on, due to air movement, this is not so noticeable).
VAV system with proportional valve control
This VAV system is similar to the previous one, but it uses proportional control valves that allow you to smoothly adjust the angle of rotation of the damper, changing throughput valve in the range from 0 to 100%. To control valve drives, SV-02 modules are used, to which JLC101 regulators (potentiometers) are connected. Since constant pressure is maintained in the channel, the air flow in each room will be determined only by the angle of rotation of the damper of the corresponding valve, and the position of the damper by the angle of rotation of the regulator handle.
The system uses drives with an operating voltage of 24V DC. They are powered by SV-02 modules, to which a cable is supplied from the power supply. SV-02 modules also allow you to broadcast information about the current position of the valve flap (0 - 10V signal) to control the actual air flow. Let's calculate the required power of the power supply: one set of the drive and the CB-02 module consumes 2.5W + 0.5W = 3W. And three sets – 9 W. The system must use a power supply that has a 15-20% power reserve, that is, at least 11 W.
Another difference between this system and the previous one is the absence balancing valve. The SV-02 module allows you to adjust the position of the valve flap in open and closed states (that is, at the extreme positions of the regulator handle) using trimming resistors located on the module board. This makes it easy to configure the system so that when the regulator is set to minimum, the damper flap remains slightly open, providing the desired air flow. Please note that in room No. 5 there is a discrete valve, which is controlled from the central lighting. By this we wanted to show that there are no restrictions on the methods of controlling air flow, and it is possible to use various technical solutions in one system.
VAV system with centralized valve control
Let's consider more difficult option VAV systems with centralized control of all its elements. The main difference between this option and the previous one is the use of JL201 electronic modules. Possessing all the capabilities of the SV-02 (they were described in the previous example), the new modules have inputs for connecting motion sensors, temperature, air flow, CO 2 concentration and others. In addition, these modules have a port for connecting to the Modbus bus for centralized valve control and remote reading of sensors connected to the module.
The JL201DP modification also has a digital differential pressure sensor, the readings of which can also be transmitted via Modbus. By connecting the modules via a single Modbus bus, we will be able to centralize (scenario) control the entire system.
The ventilation system shown in this example demonstrates various options application of JL201 modules. In addition to these modules, the system includes the following elements:
- Air handling unit Breezart 12000 Aqua.
- Valves with electric drives with proportional control.
- Regulators JLC101, CO 2 sensor.
Description of the system by room:
No. 1. There is no regulator or sensor connected to the JL201 module. Control is carried out only from the central panel via Modbus. This option can be used in an office where the ventilation is turned on by a timer during working hours.
No. 2, 3 and 4. The illustration shows possible option using one valve to service several rooms. Control can be carried out either centrally or locally using the JLC101 controller. Switching between manual and automatic operating modes is done using the same controller or using a timer.
No. 5. A JLC101 regulator is also installed in this room.
No. 6. Only a CO 2 sensor is installed in this room. Air flow is adjusted automatically to maintain the concentration value set from the remote control carbon dioxide. Thanks to this, the ventilation in this room is turned on only when there is someone there
VAV system based on CO 2 sensor
Control is possible only from the carbon dioxide sensor, any other control of the VAV system zone is impossible, joint control is also impossible (the control type is set during commissioning).
By default, a sensor with an output of 0-10V and a measurement range of 0-2000ppm is used (when using sensors with other parameters, the JL201 module must be configured via the JLConfigurator program). When configuring via JLConfigurator, you can use a signal of 2-10V, 4-20mA and any measurement range. When selecting the CO 2 sensor mode, the minimum and maximum concentration of carbon dioxide in PPM units is specified in the min and max fields. If during the operation of the zonal ventilation system the actual value of the carbon dioxide concentration is below the minimum value, then the minimum voltage (set in the previous stage) will be set on the valve actuator. If the actual carbon dioxide concentration is higher than the maximum value, the valve actuator will be set to maximum voltage. When the carbon dioxide concentration is within the min – max range, the voltage on the drive will change in direct proportion to the carbon dioxide concentration.
Air handling unit operation in VAV mode
A ventilation system based on a Breezart supply or supply and exhaust unit can operate in VAV mode, which allows you to regulate the ventilation performance (air flow) in each zone (a zone can contain one or more similar rooms). Regulation is performed using motorized air valves controlled by CB-02 or JL201 modules. JL201 modules can be connected via a ModBus network for centralized control. System capabilities and characteristics:
- Any number of autonomous zones (on CB-02).
- Up to 20 zones with centralized control (on JL201).
- Centralized control of air flow, including according to scenarios.
- Local air flow control (using a manual regulator).
- Air flow control from motion sensors, CO 2 concentration and others.
- Full configuration of JL201(DP) modules from the remote control, including changing the ModBus address.
The VAV operating mode is turned on and configured during commissioning of the system (the algorithm is described in the instructions “Setting up Breezart VAV systems”). In VAV mode, the VAV icon appears at the top of the main screen, and the Fan Speed field does not display the fan speed, but the pressure level in the duct or distribution chamber (default 10). By default, pressure control is disabled, in which case clicking on the Fan Speed field on the main screen will open the Zone Air Flow page, which will display the actual air flow (set when running the script), as well as the current flow control mode:
- Local – local government flow using a manual regulator. In this mode, the actual flow rate may differ from that specified in the scenario.
- Remote control – centralized control of flow rate from the remote control according to scenarios. If (Mixed) – Mixed control is indicated next to the name of the Local or Remote control mode, then it is possible to switch between the Remote and Local modes
- CO 2 – control by carbon dioxide concentration sensor. The CO 2 concentration measured by the sensor is displayed next to it
- Ext. cont. – the zone is turned on/off when the external contact is closed/opened.
- The message “No communication” means there is no communication with the JL201 module of this zone. To manually change the air flow, touch the desired option, with right side A slider will appear with which you can set the required air flow in the range from 0 to 100% in 5% increments.
At the stage of setting up the VAV system for zones with centralized control, you can set the actual air flow at the extreme positions of the damper damper. In this case, the air flow will be displayed not as a percentage, but in cubic meters per hour (the unit of measurement will not be displayed on the screen due to lack of space). If adjusting the pressure in the channel is allowed, then from the Main screen you can go to both adjusting the pressure (by clicking on this field) and adjusting the air flow in the zones (by clicking on the fan icon).
When the air handling unit is turned off, the actual flow will be zero and all valves in centrally controlled zones will be completely closed. At the setup stage, you can select the type of control for each zone: local control only; only centralized control from the remote control; mixed management. With mixed control, the user can independently change the control mode (local or from the remote control). To switch the zone to local control mode, you need to turn the manual control to the Min position (the control will change to Local), and then set the desired air flow level with this control. When any scenario is activated, the module will be automatically switched to Remote mode (note: if when starting the scenario, the manual control is near the Min position, the module will remain in Local mode). Zone numbers can be replaced with icons - this will help you remember which room each zone serves. To change the icon, press the number (icon) of the desired zone and hold for 3-4 seconds. A screen with a list of icons will open. Click on the appropriate icon and it will be displayed instead of the zone number (to return the zone number, click on the first icon in this list).
