Supply and exhaust ventilation: features and proper arrangement

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07 Sep 2022
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Content
  1. THE OPERATION PRINCIPLE OF THE SUPPLY AND EXHAUST VENTILATION SYSTEM
  2. SUPPLY AND EXHAUST VENTILATION: KEY FEATURES
    1. ADVANTAGES OF SUPPLY AND EXHAUST SYSTEMS
    2. DISADVANTAGES OF SUPPLY AND EXHAUST VENTILATION
  3. SUPPLY AND EXHAUST VENTILATION SYSTEM WITH HEAT AND MOISTURE RECOVERY
  4. CALCULATION OF SUPPLY AND EXHAUST VENTILATION
    1. BASED ON AIR EXCHANGE RATE
    2. BASED ON THE NUMBER OF PEOPLE
    3. BASED ON THE AMOUNT OF CO2
    4. AERODYNAMIC CALCULATION
  5. SUPPLY AND EXHAUST VENTILATION: INSTALLATION DIAGRAM
  6. Equipment for supply and exhaust ventilation
    1. Decentralized supply and exhaust system
    2. Centralized supply and exhaust ventilation
  7. FAQ
    1. What is the supply and exhaust ventilation system for?
    2. How to make supply and exhaust ventilation?
    3. Is it beneficial to use supply and exhaust ventilation with heat recovery?
  8. Our videoreviews

Nowadays, ventilation is an integral system of comfortable and energy-efficient accommodation. Modern houses have high thermal insulation characteristics (high-quality double-glazed windows and insulated external structures). As a result, fresh air flows do not get inside.

Excess CO2 negatively affects the human condition and may cause headaches, insomnia, decreased productivity, etc. When windows are open, unpurified cold air will enter the room, and this will reduce comfort and increase the load on the heating system as well. Therefore, forced ventilation is needed in the apartment.

Therefore, ventilation is a must. The best solution is to install a supply and exhaust system with recuperation, which will accomplish several objectives at once:

  • Fresh air supply.
  • Extraction of exhaust air.
  • Supply air heating by heat recovery.
  • Air humidification (moisture recovery).

Supply and exhaust ventilation with heat and moisture recovery is a rational use of energy resources. 

Before we start discussing the features, it is necessary to understand the concept of supply and exhaust ventilation.

Ventilation is a must.
Ventilation is a must.

THE OPERATION PRINCIPLE OF THE SUPPLY AND EXHAUST VENTILATION SYSTEM

Supply and exhaust ventilation is a system that provides the flow of air from outdoors into the room, as well as the extraction of already exhausted air. The key element of supply and exhaust ventilation, which is responsible for maintaining of air exchange, is an air handling unit. 

The air-handling unit is a mono-block device that contains in its casing all the main components for organizing ventilation.

The supply and exhaust ventilation system consists of:

  • air-handling unit, which includes: supply and exhaust fans, filters, air pre- or post-heaters, recuperator, automation, by-pass, measuring sensors, etc.;
  • external air grids for supply of fresh air and extraction of exhausted air;
  • air duct system (galvanized steel air ducts, Flexy air ducts);
  • silencers;
  • filters (for supply and exhaust air);
  • control air valves (throttle valves or VAV valves);
  • air supply box;
  • air distributors (slot diffuser, ceiling air diffuser, grid).

In addition to basic functions (air supply and exhaust), the equipment also performs additional functions, for example: air filtration, heating, cooling and humidification.

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Main principles of system operation

Firstly, the living area is divided into two areas – “clean” and “dirty”.

“Clean area” is the premises where residents spend a lot of time (a living room, a bedroom, children's room). The “dirty area” includes: a bathroom, a shower room, a dressing room, a laundry room, a kitchen, etc.

Thus, the supply of clean air is carried out in the key premises – the “clean area”, and the intake of exhaust air in the secondary ones – in the “dirty area”.

In order for the air exchange to be correct, the system must be in balance. This means that when supplying 100 cubic meters of air, the unit must intake 100 cubic meters. If the balance of the system is not maintained, then the efficiency of the recuperation process will decrease.

Recuperation is a process that allows warm exhaust air to warm up cold supply air to reduce energy consumption for preheating air.

So, the first basic principle of the supply and exhaust ventilation device is to supply in the “clean area” and intake in the “dirty” one.

The second basic principle is the balance of the system.

SUPPLY AND EXHAUST VENTILATION: KEY FEATURES

The engineering of supply and exhaust ventilation is a very painstaking process that requires compliance with many rules and nuances.

We already know that the air supply is carried out in the “clean area”, and the intake – in the “dirty” one. However, to organize proper air exchange, the following recommendations must be observed.

  • Implement air supply at the most remote point from the door so that the fresh airflow saturates the entire room. Next, the displaced air moves to the nearest “dirty area”.
  • The exhaust air terminal unit is also installed at the maximum distance from the doors.
  • In order for air to flow freely from one room to another, it is necessary to provide a gap under the door (up to 2 cm).
  • High-quality aerodynamics. The air duct system must be designed in accordance with the path of least resistance. That is why it is necessary to make the shortest path from the unit to the air distributor, avoiding intersections. This allows to use less material for the air ducts and to avoid noise in the system.
  • Soundproofing of the unit. The operation of the air handling unit results in acoustic noise, which will be carried throughout the entire air duct system and will create severe discomfort for residents.
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In order to avoid trouble, four silencers (at the outlet of the unit) are installed on each of the air ducts. These silencers perform the following functions:

  1. air intake from outdoors;
  2. air supply to the premises;
  3. air extraction from the premises;
  4. discharge of exhaust air to outdoors.

In addition, the wrong selection of air ducts contributes to the appearance of noise. It is necessary to calculate the required cross section so that the air speed is within the normal range and does not create noise.

  • Thermal insulation of air ducts, which carry out the intake of fresh air from outdoors and extraction of exhaust air. 

 In winter, there is a sharp temperature drop, which leads to condensation on the outside of the air ducts.

To avoid the above-mentioned problems, 2 cm thick rubber is used for thermal insulation of air ducts.

  • Air filtration must be present for both supply air and exhaust air.

Various filters are used to filter the air, these can be:

  1. G4 coarse filters (for exhaust air). Most often, this type of air filter is used to protect the mechanism of the ventilation unit from dust.
  2. F7 fine filters are used to clean the supply air from insects, dirt, dust, wool and other pollutants.
  3. Carbon filters prevent unpleasant odors.
  • The air-handling unit is installed inside the house/apartment, often in a separate room. The equipment is not recommended for installation in cold areas (attic or staircase).

ADVANTAGES OF SUPPLY AND EXHAUST SYSTEMS

Supply and exhaust ventilation has a number of advantages:

  • Provides high-quality air exchange (supply + exhaust) throughout the entire area of ​​the house 24 hours a day.
  • Supply air filtration.
  • High energy efficiency through heat recovery (plate recuperator)  or heat and moisture recovery (enthalpy recuperator).
  • Regulated air exchange (using CO2 sensors).

DISADVANTAGES OF SUPPLY AND EXHAUST VENTILATION

Supply and exhaust ventilation systems have almost no drawbacks.

Before installing the system, it is necessary to take into account the lowering of the ceilings, which is 17 cm clean (without false ceiling, etc.).

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SUPPLY AND EXHAUST VENTILATION SYSTEM WITH HEAT AND MOISTURE RECOVERY

The process of heat and moisture recovery is the main advantage of the air handling unit. This function allows you to regenerate the heat and moisture of the exhaust air, significantly reducing the p pressure on the heating system and reducing the cost of heating the supply air using a special heat exchanger – recuperator.

When using a conventional exhaust system (for example: a kitchen hood or an exhaust fan in a bathroom, etc.), heated air (heat) is removed to the outdoors.

The air handling unit with recuperation is an energy-efficient equipment, and will allow heating the supply air using the thermal energy of the exhaust air.

A recuperator is an energy-saving element of the ventilation system, the main task of which is to transfer heat from the exhaust air to the supply air.

The main types of recuperators:

Heat exchange between exhaust and supply air occurs due to the intersection of air flows. Since the recuperator consists of plates, the air flows do not intersect. Thus, clean, but already heated air is supplied to the “clean areas”.

The main difference from the classic heat recuperator is that this unit returns both heat and moisture to the room. However, the main disadvantage is rapid wear. The enthalpy recuperator is recommended to be used during the winter period. In winter, the humidity of the outdoor air drops significantly.

A rotary recuperator is a heat exchanger similar to a drum, which, due to a special element – a rotor, rotates and heats the supply air.

Rotary recuperators are not used in the household segment, as they are designed for high airflow rate.

 You can additionally find more detailed information about recuperators in our article “Air recovery system in a house or apartment”.

CALCULATION OF SUPPLY AND EXHAUST VENTILATION

Supply and exhaust ventilation schemes Implements based on air exchange calculations.

There are three main methods of the air exchange calculation:

  1. based on air exchange rate;
  2. based on the number of people;
  3. based on the amount of CO2.

BASED ON AIR EXCHANGE RATE

The air exchange rate directly depends on the volume of the room (ceiling height and area). It makes it clear how much air is replaced per unit of time. The air exchange rate is regulated by Construction Norms & Regulations and depends on the type of premises.

Thus, knowing the air exchange rate for optimal conditions of 0.6 (according to Construction Norms & Regulations), the volume of the room (ceiling height × area), and multiplying these values, you can find out the required amount of air in m3/ h.

BASED ON THE NUMBER OF PEOPLE

According to Construction Norms & Regulations, the following rates of the amount of air per person are accepted:

  • reduced comfort level – 15 m3/hour;
  • optimal level – 25 m3/hour;
  • increased comfort  – 36 m3/hour;

This calculation considers the number of people living in the house. Thus, for each room (clean area) a calculation is made. For example, if two people live in a bedroom, then the amount of air supplied is 72 m3/hour (for increased comfort). However, the living room will consider the total number of occupants, as this is the place where the whole family gathers.

BASED ON THE AMOUNT OF CO2

Such a calculation is made when arranging a variable ventilation system, and not a constant one, as in the two previous cases.

In this case, 60 m3/h per person is applied. This is how much air is needed in order to remove the CO2 that our body produces. The calculation method does not differ from the previous version (calculation based on the number of people).

To organize variable air supply, Alter Air uses innovative equipment from the Czech manufacturer Jablotron, which has no analogues in Ukraine.

AERODYNAMIC CALCULATION

When the engineer has already developed an air duct scheme, an aerodynamic calculation is performed. This calculation is very important. In the case of an incorrect calculation, the following problems may arise:

  • Incorrect selection of equipment, which can lead to a malfunction of the entire system.
  • High levels of noise in the air ducts, which leads to significant discomfort.
  • Incorrect selection of air terminal units results in high outlet speed (when supplying air). This also contributes to the appearance of drafts.

To select equipment, the resistance in the system is calculated, which considers the pressure of the air ducts themselves and local resistances (valves, air distributor units, air supply boxes, etc.).

To avoid noise in the air duct system, the air speed must not exceed 3 m/s. To achieve the required speed, it is necessary to choose the right cross-sections of the air ducts.

To ensure comfortable air distribution, the air speed at the outlet of the system should not exceed 2.5 m/s. The air speed depends on the size of the air distributor; it can be a diffuser, anemostat or a grid. It is also important that the speed is not lower than 2 m/s. If lower, fresh air will not enter the working area (where the person is), since in most cases the air supply is implemented from the ceiling.

SUPPLY AND EXHAUST VENTILATION: INSTALLATION DIAGRAM

An example of Jablotron Futura L system onsite
An example of Jablotron Futura L system onsite

Equipment for supply and exhaust ventilation

Supply and exhaust ventilation systems can be implemented not only with the help of an air handling unit, but also with the help of other devices that are cheaper.

For air supply, you can use:

  • Air supply valve – a ventilation device for airing the room, which is installed into the wall. It is the cheapest option for air flow, but not the most efficient. The disadvantage is the supply of untreated cold or warm air, depending on the season. In winter, the supply of cold air significantly reduces the comfort of residents and increases the load and costs of the heating system.
  • Breathers are devices that perform the function of supplying, filtering and heating air. This device is installed through the wall. Alter Air specialists prefer trusted brands:
  • Air supply unit – a monoblock device for air supply. Unlike the breather, the supply unit has greater productivity. Often it is used for industrial facilities.

For air extraction in the supply and exhaust system, the following are used:

  • Exhaust fans that are installed in “dirty areas” (bathroom, shower room, etc.). The main task of the exhaust system is to remove excess moisture, unpleasant odors and exhaust air.

Types of exhaust fans, depending on the principle of operation:

  1. On/Off. When the light turns on in the room, the device starts working and when the light turns off, it stops.
  2. With timer. When the light turns on, the fan removes polluted air; after the light turns off, the device continues working for 15-20 minutes.
  3. With humidity sensor. If the humidity in the room rises, the device starts to extract air, and then it works with a timer until the humidity indicators return to normal.

Alter Air prefers the following manufacturers of exhaust fans:

  • Kitchen probes, which are installed above the cooking surface to collect odors and vapors. Usually, the kitchen hood does not remove all the dirty air because it does not have enough power.

The main disadvantage of the above-mentioned exhaust systems is that warm air is extracted to outdoors. While the supply and exhaust system performs the recovery process and uses the energy of the exhaust air to heat the supply air.

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Decentralized supply and exhaust system

Decentralized ventilation is implemented by using household recuperators.

A household recuperator is a compact system for organizing local air exchange. This device is equipped with a recuperator, which allows you to heat the supply air without significant electricity costs, as well as humidify when buying an enthalpy recuperator.

Manufacturers of household recuperators:

Household recuperator Zehnder in the interior
Household recuperator Zehnder in the interior
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We will take a look at two air handling units from the German brand Meltem:

  1. Meltem M-WRG;
  2. Meltem M-WRG-II P (second generation with improved functionality).

Meltem M-WRG does not differ much from the newer model, the difference is only in the efficiency (coefficient of performance) of the recovery of 76%, in the level of soundproofing (up to 56 dB) and in the filtering system (two G4 filters).

The Meltem unit generates 100 m3/hour, which allows you to supply 100 cubic meters of clean air and remove the same amount of polluted air. One unit is able to organize high-quality air exchange in several rooms at once. For example, supply 50 m3/hour to the bedroom and 50 m3/hour to the children’s room. According to Construction Norms & Regulations, 50 m3/hour is enough for optimal comfort of 2 people. Air extraction is carried out in two “dirty areas”.

Additional CO2 sensors and humidity sensors can be purchased for better adjustment of the system.

The filtration system is represented by two filters:

  • G4 (coarse) purifies the exhaust air to protect the air handling unit mechanism.
  • F7 (fine) for filtering the supply air from fine particles, wool, insects and more.
  • Carbon filter blocks odors (optional).

System installation options:

  • Installation on a wall surface. The device is installed on the inside of the house and works as a decentralized device.
  • In-wall installation. The device is built into the wall. A special plate will remain on the surface, on which you can apply a photo or any other image, which allows you to successfully fit the installation into the interior.
  • Installation with an air duct system. This option allows you to organize both the air supply and the air exhaust.

Conventional air handling units are not designed for extraction of air from the kitchen. However, our company works with leaders in the ventilation industry, Jablotron and Faber. These manufacturers, together, have created a unique supply and exhaust system that can also remove polluted air from the kitchen and use more heat to heat the supply air.

Centralized supply and exhaust ventilation

The best solution for high-quality ventilation is a VAV system (system with variable air supply) based on Czech equipment Jablotron (Futura L or Futura M).

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The air supply to the premises is carried out based on CO2 indicators for the rooms. Sensors that are installed in each “clean area” monitor the amount of carbon dioxide.

In the case when there is no one in the house, the air handling unit operates at a minimum speed and supplies air in small quantities. With an increase in CO2, which indicates that there is a person in the room, the unit gradually increases the air supply to the desired room, reducing the airflow in rooms where there is nobody. It is worth noting that the system also operates at minimum speed. If the amount of CO2 continues to increase, then the efficiency of the unit increases until the level of carbon dioxide is normal.

The principle of variable air supply allows the rational use of energy resources and reduces the cost of operating the device. While with a constant air supply, the entire area of accommodation is ventilated and the unit operates at full capacity, using a lot of energy.

Because the system supplies air to the premises where it is needed, analyzing the information from the CO2 sensors in the rooms, this principle of operation allows you to increase the amount of air supplied by 2 times, using a unit of the same power. Instead of 36 cubic meters of air, 60 cubic meters will be supplied, which will significantly increase indoor comfort.

VarioBreeze
VarioBreeze

The innovative VarioBreeze VAV valves from Jablotron are used to regulate air exchange. The valves are installed on supply and exhaust air ducts. The cross-sections of the supply VAV valves are regulated depending on the CO2 indicators. With an increase in carbon dioxide, the valves open slightly and with a decrease, they close slightly.

Exhaust VAV valves work depending on the flow valves. This implies that the system is in balance (supply air = exhaust air).

For enhanced air extraction in bathrooms and showers, “Boost Button” is used. This device is mounted in a light switch and unnoticeable in the interior. Thus, when the light turns on, there is an increased air extraction. This mode is configured individually, depending on the needs of the customer.

BoostButton
BoostButton

Faber's equipment is used for the kitchen hood, which interacts with the Jablotron air handling units. This implies that the air extraction is carried out through the ventilation unit. Thus, a large amount of warm air energy is sent to the recuperator to supply heating, and is not discharged to the outdoors as in conventional exhaust systems.

Optionally, you can purchase CoolBreeze.

CoolBreeze is an air-to-air heat pump that can be used to heat or cool air during the off-season.

In the case when the recuperator no longer heats the supply air to a comfortable temperature in winter, an additional module, CoolBreeze, is installed on the air duct through which the exhaust air moves. In this way, the temperature of the exhaust air rises, and since the exhaust air passes through the plate recuperator, the temperature of the supply air also rises. By the same principle, the device works for cooling.

CoolBreeze is ideal for demi-season and nighttime when there is no active heat. In the summer, this device is no longer enough, and it is necessary to install an additional air conditioning system for a comfortable microclimate.

Using the Jablotron climate system is an excellent combination of price and quality.

Currently, there are no analogues of the innovative variable air supply system in Ukraine.

Закажите расчет системы вентиляции

FAQ

What is the supply and exhaust ventilation system for?

In the modern world, special attention is paid to the energy efficiency of the building. This means that a modern house has: high-quality double-glazed windows, insulated external walls, attics, and a foundation. All this helps to reduce heat loss during the heating season. As a result, the house becomes completely sealed and not ventilated.

Opening windows for ventilation is an irrational solution, since heat will leave the building.

However, without fresh air exchange, being indoors will be uncomfortable, and health problems may appear as well as fungus. 

To avoid the above-mentioned disadvantages, we recommend using a supply and exhaust system with heat recovery. This type of ventilation will not only ventilate the room, but also reduce the cost of air heating. With a help of the recuperator, the heat of the exhaust air is transferred to the cold supply air.

How to make supply and exhaust ventilation?

Creating a supply and exhaust system is a painstaking and time-consuming process. It is necessary to consider many factors: make the necessary calculations and a drawing, select an installation, carry out installation, etc.

To organize a high-quality and durable system, it is better to contact specialists.

Alter Air provides a turnkey ventilation service. We lead the project from the first consultation and design to installation and commissioning.

Is it beneficial to use supply and exhaust ventilation with heat recovery?

Supply and exhaust ventilation with recuperation allows you to use the heat of the exhaust air to heat the supply air, which significantly reduces electricity costs. Therefore, if you want to save money, we recommend purchasing this climate system.

The supply and exhaust system with recuperation will significantly reduce the cost of electricity during operation.

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  • 5 / 5

    Ольга

    Здравствуйте! Спасибо за понятную статью. Интересует, насколько актуально оборудовать такую систему вентиляции для аллергика (пыль, пыльца)? Может, есть какие-то советы, что лучше выбрать?

  • Команда Альтер Эйр

    Добрый день, Ольга! Для вас будет актуальна приточно-вытяжная вентиляция с фильтрами тонкой очистки класса F7. В оборудовании Jablotron, Meltem, Maico они предусмотрены. В другие системы их можно установить опционально.

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