The supply and exhaust ventilation system operates by consuming and exhausting air. In winter, heating of air flows is required to create a comfortable indoor climate. This task is performed by the heater. The efficiency of work directly depends on the correctness of its installation and strapping. For this reason, the connection is carried out in compliance with all rules and regulations.
Operating principle
A heater (duct heater) is a universal device that transfers heat energy from a heating element to the supply air. The device works as a heat exchanger. It consists of pipes through which air masses circulate. In pipes, thermal energy is transferred from one carrier to another.
When air enters the unit through the grate, the masses are heated due to heat exchange from the pipes. Then the fan blows around the device and supplies the heated air through the diffuser into the room. In order for the device to work silently, special sound-absorbing elements are used. When the unit is shut down, the valves block the access of cold air from the street to the system.
The heater cannot work without a piping system. For its functioning, control units are required that perform the following functions:
- Control of work. Parts provide a constant mode of operation and report failures.
- Ensuring the smooth operation of the heat exchanger. Emergency notification.
- Temperature control and adjustment. The temperature must be within the design values for uniform heating.
- Prevention of icing.
The system includes the following elements:
- Shut-off valves. These are valves for shutting off the flow of the coolant, which are made of durable materials (steel, brass). It is selected according to the power of the device.
- Check valves. They are a barrier to the outflow of fluid. The choice is made according to the diameter of the pipelines.
- Actuator and control valves. They are the main and most important part of the strapping unit.
- Manometer, thermometer.
- Valve for air removal and drainage.
- Balancing valve.
- Pump.
- Filter. A mesh with a mesh of 500 microns is used.
The installation of the system is carried out by specialists in accordance with the existing standards specified in SNiP, SP and GOST. You first need to create a drawing of the heater for the correct connection.
Varieties of air heaters
Duct heaters are classified according to the type of heat carrier. There are the following types:
- Electrical. A metal heating element is used as a heating element, which operates from the mains. The device is easy to install and install. The capacity is designed to service premises up to 100 sq. M.
- Water. These are devices in which water circulates through pipes. It is used in ventilation systems in public and industrial premises. It is necessary to install a piping unit for a water heater.
- Steam. The heater, powered by steam, has a high efficiency, high heating rate. The steam is heated to a certain design temperature. Suitable for installation in industrial buildings with a steam source. The piping of the supply ventilation steam heater is complicated, therefore it is performed only by specialists.
The choice of the optimal system depends on the type of premises, its purpose and capabilities.
Equipment selection
The elements that make up the system do not differ depending on the selected scheme. To choose the right components, you need to use the following recommendations:
- All fittings must meet technical specifications. They are calculated by the maximum value of temperature and pressure.
- The diameter of the elements must correspond to the size of the heating system pipes.
Ball valves made of steel or brass should be chosen as shut-off valves. Flanged valves are required for pipes with a diameter over 50 mm.
To simplify the work, they buy cranes with union nuts. To limit the flow, check valves are selected, which are installed on the return line or bypass of the nodes.
To control temperature and pressure, manometers and thermometers are purchased. The temperature sensor is installed on the flow and return lines in front of the heater. The pressure gauge is installed in the pump group.
To create optimal movement of the coolant, a circulation pump is installed. It is mounted on an adjustable section where it helps to overcome hydraulic resistance. Filters, valves, valves act as additional parts.
Connection diagrams
For efficient heating of the incoming air by means of an air heater, it is necessary to make the correct connection. There are several installation schemes, which include:
- One ventilation circuit and one heater. This is the simplest scheme, in which one heating device is located at the inlet or any other section of the channel. This connection is used for seasonal heating and does not have a backup heat source.
- Two ventilation circuits and several heaters. This is a more complex scheme, suitable for installation in rooms with complex shapes. Suitable for year round use. There are several strapping knots. The first circuit is used for heating in autumn and winter, and the second for summer. Due to the large number of devices, the system can work continuously even in the event of an accident at one of the piping nodes.
The classic strapping unit includes the following elements:
- Circulation pump. It is used in water systems and propels liquid through pipes.
- Compressor and condensing unit. It is used as an external unit in the piping of the cooling system.
- Temperature and pressure control devices.
- Locking mechanisms.
- Bypass.
- Filter.
- Two-way or three-way automatic valve.
- Tubes, connectors and other parts to connect the mixing unit for ventilation.
The connection diagram of the strapping unit can be made using rigid and flexible connections. Rigid piping is the simplest connection using metal pipes. Suitable when the exact location of the heater is already known. Flexible hose is the most complex and is made using corrugated pipes.
Temperature control
Temperature control is the most important task of the system. There are two ways to adjust:
- Quantitative. This is an outdated method in which the temperature directly depends on the volume of the coolant.
- Qualitative. A more efficient method in which the coolant is consumed linearly. This is done using a three-way valve and a pump. The possibility of leakage is excluded.
Experts use the second method. It is compatible with any heater connection diagram.
Ventilation system
The choice of the optimal ventilation scheme is influenced by the required temperature, heating intensity, heat carrier source, pressure difference. There are several systems:
- Air handling unit piping using a two-way valve.It is placed at the point of entry without an additional heat exchanger. As a result, the valve acts as an intermediate buffer and dampens the water flow pressure. The disadvantages of the scheme include the risk of freezing at low temperatures. Installation of a pump is required.
- Using a three-way valve. The result is two strapping systems. In the first case, the separation of water flows is carried out, and in the second, their mixing. The scheme is used in autonomous heating networks.
With any scheme, installation of the hood is required. By maintaining a balance between incoming and outgoing air flows, the design temperature in the room is maintained.
