Air handling unit: types, comparison, and selection and operation rules

Natural air circulation system often is faltering - its performance is dependent on natural factors and the use of sealed glass units. These deficiencies deprived of forced ventilation.

To normalize the air used air handling unit - a practical and efficient solution. The variety of HVAC equipment allows you to choose a model for the specific operating conditions. However, to determine the appropriate device is sometimes problematic, right?

We will help you resolve this issue. This article provides information about the principles of operation and characteristics of different types of air handling units. To facilitate the selection, we identified the main characteristics and parameters of the devices that are sure to be taken into account when buying.

Constituent elements of forced ventilation

Supply and exhaust unit - the main component of a ventilation system with impulse. The device provides the normalized air circulation in the closed space - supplying clean exhaust streams and output masses.

Ventilation module is a set of equipment, enclosed in a single casing (monoblock unit) or collected from the composing elements.

The design of supply and exhaust unit necessarily includes the following elements:

1. Fan. Basic set for artificial ventilation system. The SSP branched network installed duct centrifugal fans, supporting a high air pressure. In the portable SSP application admissible axle models.
2. Air valve. Mounted in the outer lattice and prevents air from entering from the outside when the system is off. In its absence, the room in the winter will be cold seep flow
3. Magistral duct. two line channels involved in the system: one - feed, and the second - the air ejection. Both networks run through the SSP. The first duct connects the supply fan, to a second, respectively, exhaust.
4. Automation. Fitting is regulated by integrated automation system, responsive to the sensor readings and parameters are set by the user.
5. Filters. complex filtering is used for cleaning the incoming mass. At the entrance of the air intake duct is placed rough cleaning filter, its task - to hold down, insects and dust particles.

The main purpose of primary treatment - the protection of the internal components of the system. To "fine" filter in front of diffusers are installed photocatalyst, carbon or other type of barrier.

Some systems are equipped with additional functional: cooling, conditioning, moisturizing, multistep purification system and air ionization.

The operating principle of supply and extract complex

Work SSP cycle based on the two-loop transport.

The whole process of ventilation can be divided into several stages:

1. Fence airflow from the street, its purification and supply to the distributor through a duct.
2. Receipt contaminated masses into the suction channel and their subsequent transport to an output grating.
3. EXHAUST jets outward.

the circulation circuit may be supplemented by heat energy transfer stages between the two streams, additional heating of the incoming air, etc.

forced operation of the system provides a range of advantages in comparison with natural air exchange:

• maintaining the set parameters - sensors react to the change in the atmosphere and will adapt mode SSP;
• filtering incoming flow and the possibility of processing - heating, cooling, humidification;
• savings on heating costs - important for devices with recuperation.

The disadvantages of using the SSP are: the high cost of the vent complex, complexity of installation after the repair and construction work and noise effect. The one-piece units last minus eliminated through the use of a soundproof enclosure.

Types of plants: the device features and operation

Cost, performance, power consumption depends on the functionality of the SSP. The variety of models is divided into the following groups: units with heat recovery, units with heating and air conditioning. A separate category - the "mobile" devices.

Supply and exhaust unit with heat recovery

Forced ventilation system in addition to advantages described above has a significant drawback - a significant increase in heat loss. Together with the spent air "escapes" and worked out by the heat of the heating system.

The costs of the order of 60%. Solving the problem - the transfer of energy from the exhaust airflow to the supply.

To date, most of the air handling units are manufactured with heat recovery. Despite the high cost of equipment, the feasibility of regenerative system economically feasible.

The values ​​of "heat exchanger" efficiency:

• 30-60% - low level heat recovery;
• 60-80% - a good performance indicator;
• more than 80% - high heat.

Interestingly, even the presence of the heat exchanger with an efficiency of 30% is economically profitable SSP basic configuration without the heat exchanger. The average payback period of recuperative AHU - up to 5 years.

The effectiveness of the SSP, airflow movement scheme, power consumption and price of the module depends on the constructive exchanger.

There are several types of heat exchangers:

• rotary;
• plate;
• heat pipes;
• camera module;
• glekolevy unit.

Widespread first two models.

rotary heat exchanger

a cylindrical rotary heat exchanger with corrugated metal plates placed in the SSP housing. In the course of work alternately compartments filled differently directed air flows.

Compensation heat is 60-90%.

Additional benefits:

• partial return of moisture;
• economical power consumption.

the drum rotation speed can be controlled, thereby selecting the intensity level of air exchange and efficiency.

Arguments against a drum modification:

• podmes "mining" to fresh stream - 3-8%;
• partial transfer of odors back into the room;
• acoustic pressure from the revolving rotor;
• the need for regular maintenance of moving parts;
• large size.

Due to the complexity of the SSP mechanism with rotary heat exchanger plate are more expensive modifications.

Plate heat exchanger

Ducts "meet" in a sealed unit with multiple channels. The compartments are separated by heat-conducting partition walls.

Arguments for":

• Clean air supply without admixture of "mining";
• reasonable price;
• easy setup and module reliability - no moving elements.

Plate converter efficiency - 70%. The main disadvantage - the formation of condensation or ice in the winter, the exhaust duct. Job "defrost" mode (warm redirect flow bypassing the cartridge) lowers the efficiency of the system by 20%.

Now the market there are a lot of supply and exhaust ventilation systems with heat recovery from different manufacturers. With a similar set of characteristics, they differ in price, quality, service area and a variety of other criteria.

So, be sure to look at the supply and exhaust air handling unit with plate heat exchanger and integrated automation of NavekaWhich in recent years this decision has proven itself very well in the market because of their reliability and relatively quiet operation. Integrated management with the help of remote control, monitoring on an external LCD display, setting work schedules and much more already built right into the unit.

Among other brands we advise to pay attention to the recovery system from Mitsubishi, Maico and VENTO.

Energy-efficient heating units

A recovery is often not enough to fully compensate for the temperature difference counter flows. This function takes the built-in heater. Furthermore, the element to protect the heat exchanger from freezing.

two types of heaters are used in the SSP: water and electric. Let us examine each in more detail.

water heating

In case of forced ventilation units arranged radiator with tubes through which coolant is circulated. The coil has fins to increase the contact area with passing air jets.

Liquid heating element comes into operation, if the outlet of the heat exchanger the supply air is colder than a predetermined temperature.

electric heater

Fitting with electric heater can heat the feed air to higher temperatures than the "water" modification.

However, the electric heater to more demanding operating conditions:

• airflow rate - 2 m / s or more;
• supplied air temperature in the range 0-30 ° C, humidity - 80%;
• TAN recommended before installing additional filter.

Compared with the water heating electric unit, in terms of operation, more expensive - increased charges for electricity.

Complexes conditioned

Some models combine mechanical ventilation and air conditioning options. All elements are grouped into a single set of thermal insulation. A striking example of multi-functional equipment - a series of installations "Climate".

In the present circuit reversible heat pump - filled sealed freon loop is connected to the heat exchangers in the exhaust and the supply duct.

Working with SSP conditioning occurs in two modes:

1. Cooling. A heat exchanger for supply air acts as an evaporator, and decreases the temperature of the incoming air. In turn, the heat exchanger-condenser is cooled by cool air flowing from the room.
2. Heat. Recuperator exhaust air gives off heat "mining" fresh air masses. At the exit of the SSP before entering the house possible additional heating of air.

Operation Mode is automatically thanks to regulators and sensors, read the parameters of the atmosphere.

Portable non-ducted installation

An interesting solution for closed spaces - blowing mobile ventilation systems, with purification, heating, air cooling.

Distinctive features of portable modules:

• no bulky air ducts;
• installation inside the ventilated premises;
• compact dimensions and can be mounted in 2-3 hours;
• versatility: inflow, processing and output of air mass;
• low noise level - in the range of 35 dB;
• the absence of drafts.

Everything for decentralized ventilation must be installed portable SSP in each room.

Non-ducted AHU is used mainly in public buildings (lecture, exercise, training rooms, etc.).

Rating mobile HVAC equipment is given in this article.

Varieties of mounting method

There are three options for installing the ventilation module:

• floor;
• wall;
• "Podshivnoy".

Floor installation characteristic of high and bulky fan unit with an air flow of 8000 m³ / hr. Despite the presence of vibration isolation of ventilation sections solid foundation required for installation of volumetric modules.

Wall-mounted models have a small capacity - up to 1500 m³ / h and a compact size. Installation is carried out by means of anchoring to the wall, the connection of ducts from above. The unit can be placed in a technical room (balcony, bathroom, dressing room).

The main advantage of suspended models - concealed installation. However, to install the unit in operational use have partially "activate" the height of the ceilings.

The main parameters of the AHU selection

Construction and installation of ventilation systems It requires considerable capital investment and labor costs. The approach to the selection of the "heart" of the ventilation system is based on precise calculations and analyze a number of parameters.

Evaluation and calculation of the technical characteristics

First of all, it should define the appropriate values ​​performance and static pressure.

Performance

setting calculation is based on the norms of air SNIP, the appointment of the room, the area of ​​service and number of guests.

You must perform two calculations (number of people, and ventilation rate), compare the rates and select the greatest value.

EXAMPLE determine the performance (L) at predetermined Housing conditions:

• number of family members - 3 persons;
• House area - 70 square meters;
• ceiling height - 3 m.

Formula 1. living calculation on the number of:

L = N * norm,

Where:

• N - number of occupants;
• norm - Air flow rate (not less than 40 m³ / h).

L = 3 * 40 = 120 m³ / h.

Formula 2. Calculation of the ventilation rate:

L = S * H ​​* n,

Where:

• S - area;
• H - height;
• n - normalized rate of air exchange.

L = 70 * 3 * 1.5 = 315 m³ / h.

Conclusion: to provide sufficient air circulation is required installation capacity not less than 315 m³ / hr.

Typical indicators ventustanovok:

• 100-500 m³ / h - apartments and individual rooms;
• 500-2000 m³ / h - private households, cottages;
• 1000-10000 m³ / h - industrial buildings, shops, offices.

static pressure

Value indicates the pressure generated by the fan to provide the resistance to the air circulation path. The exact calculation of static pressure requires consideration of the resistance of all network elements.

"Manual" to perform the calculation is difficult without the appropriate experience. Experts employ software package type MagiCad.

These data are relevant specifically for modular ventustanovok rather than typesetting systems, which is necessary to take into account the pressure drop on the air valve, heaters, filters and other components.

In addition to the designated parameters should be evaluated:

1. Energy efficiency. For each of the possible models have to calculate the cost of electricity for 1 year with the mode of operation in summer and winter. Energy rating indicates the ratio of consumed energy to the amount of heat produced.
2. Efficiency heat exchanger. Compare the values ​​of efficiency in various operating modes SSP. The high rate of efficiency in the plate heat exchanger with double cassette and the intermediate zone - efficiency reaches 70-90%.
3. Heater power. A typical figure for household ventustanovok - 3-5 kW.

It is better to give preference to models with automatic fan speed reduction to adjust the load on the network.

The noise level and the degree of filtration

Acoustic power shows how "loud" will work assembled unit.

The sound effect is determined by two quantities:

• LwA - the degree of acoustic power;
• LpA - the sound pressure level.

To assess the real "noise" should be the first indicator. Different manufacturers may be measured acoustic power by various procedures, so the same values ​​are sometimes distinguishing result in practice.

Quality of incoming air used depends cleaning systems.

Possible filtration stage:

• barrier against large street dust, hair and lint - rough cleaning filter G4, G3 with 90% efficiency;
• protection against fine dust in 1 micron - filter class F7-F9;
• absolute cleansing, providing a barrier against particles 0.3 microns - HEPA-filters (H10-H14), efficiency - 99.5%.

For residential buildings just the first two stages of cleaning. Filtering Highly used in medical institutions, the premises for the production of pharmaceuticals, foodstuffs, electronics.

Ease of use: the necessary functionality

Household SSP equipped with built-in automation systems, control panels, LCD display with a withdrawal of all ventilation parameters. Besides the basic options (adjustment of fan speed, temperature) welcome the availability of practical features.

Timer. The scenario control allows to optimize operation for a certain time of day or day of the week.

Restart. Ability to automatically turn on and save the settings in the event of a power failure.

Indicator filter pollution. Convenient option - warning of filter element replacement. Tech model equipped changes in pressure sensors on the air filter input - at pollution pressure drop increases.

Self-diagnosis. Any technique with time breaks down. Useful if Automatic 'alerts' on of the fault - this will help to timely identify and troubleshoot the problem.

Conclusions and useful videos on the topic

Energy-efficient ventilation system with heat recovery suspended type Daikin VAM / 800FB:

The device features and technology of installation of a portable supply and exhaust module Vents Micro 60 / A3:

SSP 400 by Ventrum c electric heater and rotary heat exchanger:

Construction of the ventilation by means of supply and exhaust module used in different purposes and the meter installation.

Providing quality of air depends on the literacy of calculation and selection of HVAC equipment. If there is any doubt in their own abilities, to determine the parameters and the development of the project is better to turn to professionals.

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