Cottage ventilation: options for organizing an air exchange system + design rules

In a private home, landscaping and comfort are important. A comfortable microclimate will be provided by heating and ventilation of the cottage, civilized conditions will be created by water and electricity supply, sewerage and gas supply.Ideally, all systems are designed simultaneously, taking into account their further interaction.

We will talk about how to organize stable, complete air exchange. We will tell you which scheme is better to prefer and how to choose equipment that will work perfectly for the benefit of the owners. You will learn all about the intricacies of designing an autonomous ventilation system.

Ventilation options

Impeccably functioning building ventilation means not only cool, but also clean air that meets all sanitary standards. It would be a serious mistake to believe that a conventional hood or air conditioner will solve this problem, since the fresh air added by the climate system simply combines with the exhaust air, diluting it, while bacteria and odors remain.

Due to widespread widespread sealing, the rules of air infiltration, widely used in construction during the Soviet era, no longer work. At that time, for ventilation of apartment buildings built from environmentally friendly building materials, there were enough cracks in wooden frames and exhaust ventilation ducts.

Each room in the cottage should be regularly ventilated and completely “washed” with a flow of fresh air. Efficient ventilation ensures an optimal microclimate

Nowadays, for the sake of sealing, effective seals are installed in window and door frames that prevent natural inflow.Building structures use impermeable films and insulation materials that prevent not only the leakage of thermal energy and the penetration of moisture, but also the flow of air.

All this saves energy resources, but leads to difficulty in natural air exchange between the street and the interior of houses. In order to ensure a regular supply of fresh air to confined spaces, ventilation is installed. It can be natural, mechanical and mixed.

Principle and operation of the gravitational system

The natural system that provides regular air exchange in cottages operates due to the forces of gravity. The movement of air flows in it is justified by the difference in pressure, temperature and air density outside the windows and inside the building.

Cool street air is drawn in through supply valves, open vents, and plastic transoms slightly opened for micro-ventilation. A new fresh portion pushes the waste air mass to the exhaust, which in private buildings can be located in the ventilation shaft, in the ceiling with access to the attic, and then to the street, or through the wall directly to the street.

The draft force in the exhaust pipe is largely influenced by the wind and the cross-section, length and other parameters of the ventilation ducts. However, this only works when the outside temperature is no more than 12-15 degrees Celsius; when the values ​​increase, the efficiency of the hood decreases significantly.

The gravity type is the cheapest and easiest to implement option for installing an air exchange system. There is practically nothing to break in it, but there may be malfunctions. They happen due to equalization of pressure inside and outside the cottage

In winter, on the contrary, the air flows upward intensify, and the heat “flies out the chimney.” There are methods to improve work performance natural ventilation system — installing a deflector or check valves on the channel, but this does not fundamentally change the situation.

According to sanitary standards, the volume of incoming clean air is:

• 3 cubic meters/hour per 1 sq. meter of rooms;
• 25 cubic meters/hour for bathrooms;
• 35 cubic meters per adult.

For convenience, another standard is often used - the air exchange rate, which reflects how many times the air in the room should be replaced within an hour (in Russia this figure is at least 0.35 times / hour).

In order to ensure air movement in cottages with sealed windows, exhaust and supply valves are used. If the valves are equipped with fans, the natural system becomes a mixed system.

In practice, the discrepancy between the quality and composition of the air mass and sanitary and epidemiological standards is manifested in the following negative factors:

• in violation of the temperature regime;
• in the appearance of dampness, mold fungi;
• in the manifestation of tobacco smoke and kitchen odors;
• in increasing carbon dioxide levels.

The main advantage of the gravity type of ventilation is its simplicity and minimal costs. After all, the natural scheme does not fully fulfill the functions of air renewal assigned to it during the hot period, when for the same gravitational reasons the air can move in the opposite direction: from the house to the window.

Mechanical ventilation and its types

In order to prevent such phenomena and balance the flow of fresh and polluted air, equipment for mechanical (or as it is called forced) regulation of air exchange is installed in cottages. Mechanical ventilation systems include: not only supply and exhaust devices, but also a supply and exhaust complex.

Installation of systems involves the installation of units and blocks for the supply and exhaust of air into the air duct system (their simplest representatives are kitchen hoods and duct air conditioners).

The supply and exhaust unit is a grouping of supply and removal into one monoblock. This class also includes circuits with fans installed simultaneously in the exhaust and in the supply air. Note that in supply and exhaust circuits Only the exhaust or only the supply always works, and the owner has a choice of which is preferable to use.

When planning the supply and exhaust ventilation of a cottage, one should take into account an important condition for the normal operation of the system - clean air must flow into all residential, utility and household premises. The hood is installed in areas with unstable humidity and temperature: in bathrooms, kitchens, showers, etc.

In addition to the main premises, in which it is necessary to ensure a healthy, comfortable environment with the help of ventilation, most country houses have a large number of technical, utility and special premises.

Depending on their purpose, they require an individual approach to organizing their maintenance:

• Baths, saunas and swimming pools require ventilation with humidity control.
• In a fireplace and boiler room with an atmospheric gas boiler, it is necessary to maintain combustion by supplying oxygen.
• In dressing rooms and pantries, simple ventilation is sufficient.

If clean air enters the living rooms, children's rooms and bedrooms, and is removed from the restrooms, bathrooms and kitchens, this is a typical example of properly designed cottage ventilation and a well-designed organization of any type of system, regardless of the driving factor, gravitational or mechanical.

Exhaust vents are required to remove the air flow. ventilation pipes. They are round and rectangular in cross-sectional shape, and rigid and flexible in degree of rigidity. Aluminum and polymer corrugated air ducts are flexible.

Due to the corrugation, flexible ones have the greatest resistance, but there are situations when they cannot be avoided. Turns are easier and faster to make with corrugation. It is also installed in areas that compensate for the linear thermal expansion of plastic ventilation pipes and ducts.

Ventilation ducts in cottages are laid hidden and open. In the first case, they are laid during the construction of walls, in the second, they are laid on top of structures. Most often, open air ducts are hidden under suspended ceilings.

Pipes for ventilation devices can be rigid or flexible. Rigid ones are made from aluminum, welded and spirally wound steel, and plastic. Materials combine lightness and wear resistance

When installing a standard supply ventilation system, two difficulties appear over time:

1. a large amount of thermal energy spent on heating the incoming air and going into the exhaust pipe;
2. insufficient level of humidity indoors during the cold period.

Installing a recuperator quickly and effectively resolves these difficulties.

Supply and exhaust system with recuperator

Nowadays they are increasingly used air handling units with a recovery function, the process of heat exchange between the exhaust warm flow leaving the room and the incoming cold air.

Depending on the coolant that heats the air, recuperators are water and glycol. Depending on the type of heat exchanger recovery devices divided into plate and rotary. A feature of the rotary is a rotating drum-heat exchanger and the absence of freezing.

In systems with heat recovery, the exhaust air flow is used to increase the temperature of the fresh portion drawn in by the device from the street

Recuperators are produced for installation on the roofs of service buildings. There are models located in the attic space, and there are also apartment options that handle separate housing in high-rise buildings.

The characteristics of the plate model depend on the material of the heat exchanger cassette (plastic, aluminum, cellulose and stainless steel). Both types of recuperators are considered the most popular due to their simplicity, reliability and high efficiency; they are effectively used in ventilation systems of cottages.

Based on the principle of reusing exhaust air, recuperators are divided into plate and rotary. In the first, fresh air is only heated by the exhaust flow passing behind the adjacent plate, without mixing. In the second, a drum rotating in the housing partially mixes the fresh flow with the waste

Application supply and exhaust devices with recovery function maintains comfortable conditions and provides:

• relative humidity, by dehumidification or humidification;
• balance between the volume of supply and exhaust air;
• comfortable air temperature by cooling it with air conditioners or heating it with heating devices.

Ventilation units with a recuperator are an energy-saving system that allows you to save thermal energy up to 50% in winter, while usually with the onset of cold weather a large amount of it is spent on heating clean supply air.

In the arrangement of ventilation systems for apartments and private cottages, plate heat exchangers are mainly used. They are more compact, quieter and easier to maintain.Rotors are used to equip networks of industrial and commercial facilities and place them on roofs

The systems partially heat the incoming flow, and the built-in heater brings the temperature to the desired value.

Technical aspects when developing ventilation

When choosing equipment for a ventilation system, it is necessary to use several basic calculation indicators. For example, by multiplying the values ​​of the room volume and the air exchange rate, you can obtain the value of the fan production capacity required to fully service the cottage.

Those who are thinking about how to properly install ventilation in a cottage should naturally take into account possible losses and choose a fan with a reserve. One important point should be taken into account - the exhaust system equipment should be 10-15% more powerful than the supply system, so that used air does not accumulate in the room.

To properly organize ventilation in a cottage, a number of important factors must be taken into account:

1. Location of the exhaust duct route. Pipes should be placed predominantly vertically and straight, preferably without turns (since each turn reduces the draft by 10%) and of the same diameter along the entire length of the route.
2. Exhaust pipe height. The mouth of the exhaust pipe should rise above the roof of the cottage by at least half a meter (the air should be discharged above the roof). Installing a deflector also significantly increases the air flow circulation (up to 20%).
3. Section and dimensions of ventilation ducts. The round cross-section is considered the most cost-effective, and in practice, rigid round ventilation ducts are more often used due to ease of installation, lowest resistance and, as a consequence, high air flow intensity.

Will familiarize you with the rules for calculating the area of ​​air ducts next article, which is worth reading for all owners of country property.

Also, to enhance traction, whenever possible, use the maximum diameter and length of the pipe being laid.

To form normal draft in the exhaust pipe, you should adhere to the standards for its height. If there is less than 1.5 m between it and the ridge, it should rise 0.5 m above the ridge ridge

When developing a supply and exhaust system, it is necessary to remember some technical points:

• the amount of incoming and removed air must be balanced;
• clean air is delivered to all rooms, and dirty air is removed from areas with unstable humidity and temperature conditions;
• ventilation from the bathroom and kitchen hood cannot be combined into one channel;
• the speed of circulating flows in exhaust pipes and air ducts should not be more than 6, and at the outlet 3 meters per second.

A mechanical ventilation system is certainly more productive than its natural “sister”. Its operation is completely unaffected by weather data; its activation and deactivation can be automated. However, it is much more complex and expensive in design.

Conclusions and useful video on the topic

The following video will introduce you to the steps of installing air ducts:

The operating principle of the gravity ventilation system is presented in the video:

Ventilation hood design guide:

So, in a cottage, regardless of what building material it is made of and in what area it is built, complete air exchange is necessary.A reasonable choice would be supply and exhaust ventilation, the development of which should be included in the project.

Knowing the principles of organization, you can easily cope with the design of the gravity system without the involvement of builders. It is better to entrust the design and installation of mechanical ventilation to heating engineers.

Would you like to share your own experience in constructing a ventilation system? Do you have information on the topic of the article that may be useful to site visitors? Please write comments, ask questions and post photos in the block form below.