Ventilation

- is an indispensable element of any building. Studies show that we spend 60-90 % of our lives indoors, and the quality of the air we breathe has a direct impact on the microclimate and our well-being. The importance of air exchange control systems in residential and commercial buildings is undeniable: properly functioning ventilation ensures sufficient oxygenation, adequate humidity and quality removal of contaminated air.

The building industry offers different ventilation systems: supply, exhaust, and supply-exhaust ventilation systems. Units with recuperation are popular. In industrial areas, systems are installed with fume extraction, cooling, supplementary humidification or dehumidification.

How to understand the installation and its purpose and choose an option that will meet the customer's needs without costing too much? How is the ventilation system organised and what are the responsibilities of each element? In this publication we present a detailed overview of the modular supply and exhaust ventilation system.

Composition of supply and exhaust ventilation

Supply and exhaust ventilation: purpose, design, function of constituent elements.Air exchange system with supply and exhaust - one of the most popular on the market. The secret of its popularity is its versatility and functionality. This type of equipment is optimal for large spaces and copes well with the task of regulating air exchange in shopping centres, cinemas, restaurants, factory halls, etc.

The supply and exhaust unit is the "heart" of the whole ventilation system, supplying fresh filtered air, removing old air and using heat.

The most modern solution to ventilation problems in residential and commercial areas is a supply and exhaust system with heat recovery (heat recuperation systems). This is the best and most efficient form of ventilation by far. The supply of fresh and exhaust air to the outside is controlled. This allows the exchange rate to be adjusted according to actual needs.

Another important advantage of supply and extract ventilation is the possibility of recovering the exhaust air heat, which significantly increases the energy efficiency of the building.

Mechanical supply and exhaust ventilation consists of an air inlet and an air outlet, ducts and a central unit.

How the ventilation system is organised is discussed below.

The main elements of a ventilation system:

• supply and exhaust ventilator;
• heat exchanger;
• filters;
• ventilation duct grid;
• supply and exhaust grates;
• heaters;
• automation.

The main advantages of recuperation are:

• increased indoor comfort;
• heating energy savings of up to 80 %;
• fresh air purified by filters.

Schematic diagram of the modular supply and exhaust ventilation with recuperator.

Supply air
The supply air grate shall be used for the intake of fresh air from the outside. It consists of an external grate, a transfer box and a flange for connection to the ducts.

The air inlet grate is best installed on the external walls of the building, away from windows, if possible on the windward side of the building. This will create a certain overpressure of the supply air relative to the exhaust air, which will ensure a natural air supply. If there is no convenient access to the outside air intake, grate guards should not be used. Over time, dirt accumulating on the grates will create additional significant resistance and may become a source of noise.

Air filter
Filters are used in ventilation systems to protect against contamination that can cause malfunctioning of the equipment and damage to certain components. Air filters are also used to ensure adequate air quality for users inside the building. The products are characterised by a parameter such as filtration efficiency (trapping contaminants with the least possible resistance to air flow).

Recuperator
The recuperator is the basic element of any supply and extract ventilation system with heat recovery. It provides air exchange in a building by extracting exhaust air and supplying fresh filtered air. The 'heart' of the recuperator is the heat exchanger. Its operation determines the efficiency of the entire recuperation system. The design of the heat exchanger - its type, shape, the material it is made of, as well as the method and precision of its manufacture - is very important.

Channel heaters: water and electric heaters
Channel heaters are one component of a functional ventilation chain that provides heating to the air during air migration through the duct. The appliances are divided into electric and water heaters according to the principle of energy transfer.

Water to air heater is a heat exchanger in which air receives heat from hot water heated in a boiler or supplied from a central heating system;
An electric channel heater is powered from the mains and converts electricity into heat energy.
The choice of one or the other heating source largely determines the final cost of installing and operating the ventilation system.

Water and freon coolers
The purpose of these elements is to provide high quality cooling of the air flow.

A freon channel cooler is a heat exchanger whose main purpose is to cool the air using freon. This is compressed in a heat exchanger circuit which in turn drives a condenser-compressor unit. Freons 407, 22, 410 are normally used for filling.

Water coolers are designed for both air cooling and dehumidification. They are actively used in refrigeration applications. The refrigerant in such systems is water, sometimes glycol may be added.

Channel exhaust and supply ventilators
This device ensures efficient air circulation within the system. The robust construction and the use of a powerful electric motor ensure high operating efficiency and reliability as well as resistance to adverse mechanical influences.

Ventilation air ducts
The correct selection of elements allows efficient air distribution in different types of buildings and individual rooms. These elements are safe to use, hygienic and resistant to external influences.

Avoid sharp bends and steep turns when installing ducts. Existing chimney outlets may be used as ventilation outlets. However, additional flexible PVC ducts shall be installed and connected to the ventilation system using a suitable flange. It is best to use insulated noise absorbing ducts.

The use of corrugated or flexible ducts is only acceptable if we are sure that the ducts are laid in a relatively warm environment and with sufficient insulation of 25 mm thickness.

Backflow valve
This element is a design in which the valve blades on the axis prevent air from entering the space. The air masses in the check valve move in one direction only and if this suddenly changes, the device closes, thus preventing cold air from entering the building.

Silencers
Silencers reduce the noise from ventilators in ventilation ducts and prevent sounds from adjacent rooms from entering.

Due to silencers, the appropriate acoustic parameters can be maintained, reducing noise levels even in rooms that require high acoustic comfort, such as bedrooms or reading rooms. Noise can be caused by more than just air movement through ducts. It can also be caused by incorrect installation or poor sound insulation. Acoustic silencers are an indispensable element of any ventilation system.

Main selection parameters
We have discussed above the installation and functional purpose of the main design elements of supply and exhaust ventilation with heat recovery. In addition, the prospective owner should take into account the following parameters when selecting a suitable unit:

• weight;
• the noise generated by the control panel;
• the degree of heat recovery (it is useful to consult the efficiency diagrams for dry air heat exchangers);
• energy consumption (the unit operates twenty-four hours a day, so energy consumption parameters are very important);
• cost and availability of air filters (filters should be changed every 3-6 months);
• reliability of the ventilators (the use of ventilators from well-known manufacturers guarantees a long service life).

Conclusions
A basic knowledge of the design of ventilation systems, their purpose and types is essential for the optimal selection of a suitable design for commercial and domestic applications.

Our aim is to advise contractors and owners to simplify the decision-making process in selecting suitable equipment for quality ventilation of residential and industrial premises and to avoid the risk of commercial tricks by unscrupulous vendors.