During the construction of a private house, maximum attention is paid to the quality of enclosing structures, as well as ensuring protection from the negative effects of the environment. At the same time, over time, during the operation of the building, the owners begin to notice that in order for the air in the room not to be heavy, they often have to ventilate the premises, which causes some discomfort (especially during the cold season).
In the last century, windows and doors were not as tight as modern ones, so minimal ventilation was provided. Now, in order to organize sufficient air exchange with ventilation in all rooms of a private house, it is necessary to take care of the design of the ventilation system at the design stage of the house.
Why is it necessary to install a ventilation system
In the last few decades, the need for organizing a ventilation system has increased for the following reasons:
- All amenities are located inside the building;
- Fireplaces or heating stoves are installed that require a constant supply of air to function properly;
- In the basement, pools and saunas are often built, to remove moisture from which not only powerful ventilation is necessary, but also a properly selected air dryer;
- When constructing building envelopes, materials with minimal air permeability are used to ensure maximum thermal insulation of the building.
A properly designed and installed ventilation system will avoid the following problems:
- The appearance of mold due to high humidity (the accumulated condensate from moisture is an excellent environment for the development of microorganisms);
- Incorrect operation of the fireplace due to lack of supply air to maintain the flame and the release of combustion products outside the building through the chimney;
- Dizziness and loss of strength due to the high concentration of carbon dioxide in the air;
- The spread of odors from the kitchen and bathrooms throughout the house;
- Accumulation of grease on walls and furniture due to the absence of an exhaust hood over the hob.
Many owners of private houses think about the organization of ventilation only after the occurrence of the problems described above. However, in this case, its installation will take much more time and effort. It is necessary to get acquainted with the principle of operation of the system before the start of construction work at the design stage of the facility.
Types of ventilation systems
The task of the ventilation system is to replace polluted indoor air with clean outdoor air. This can be done both naturally by building exhaust ducts and completing plastic windows with elements for micro-ventilation, or mechanically using special equipment. The first method is not recommended, especially for houses with a large area, for the following reasons:
- Natural ventilation operates due to the difference in pressure between supply and exhaust air, which is removed using vertical ducts. In summer, the parameters of indoor and outdoor air are almost equal, so the system will not be effective;
- In winter, cold supply air will cause inconvenience.
To maximize the cost of the system, you can put the fan only on the supply or only on the exhaust. So the efficiency will increase, but the discomfort from drafts will remain. In addition, natural ventilation ducts are impossible or very difficult to install if the house is already built. In this case, fully mechanical ventilation is better, which can be of the following types:
- Supply and exhaust.
- Ventilation with recuperator.
In the first case, fans are installed for exhaust and inflow. To ensure maximum comfort, the supply system includes: a filter (to trap dust from the street), a heater, a dehumidifier or an air humidifier, if necessary. The heating element can be electric or water. In severe frosts, the energy consumption for heating a sufficient amount of air is quite significant, so it is recommended to use a heat exchanger that heats the supply air at the expense of the exhaust air. The cost of such equipment is higher, but operating costs are significantly reduced. Depending on the volume of the house and the type of recuperator, its payback period is from 5 to 10 years.
Calculation of the ventilation system
The calculation of the ventilation system is the determination of the amount of air required. For industrial buildings, it is necessary to carry out a complex calculation, taking into account heat inputs and emitted pollution by all installed equipment. In the case of residential premises, everything is somewhat simpler. It is sufficient to use the standard values specified in the relevant standards and regulations. Each room is calculated separately depending on its purpose and individual characteristics using one of the following methods:
- By multiplicity. In some rooms, the necessary air exchange does not depend on the number of people or the equipment located in them. The multiplicity is a parameter indicating how many times per hour the polluted air should be replaced by fresh air from the street. For example, in dressing rooms — 1.5 times, in showers — 5 times;
- By the number of people. In this way, air exchange is calculated for residential premises (living room, bedrooms). The optimal value is at least 30m3/h per person;
- According to the rules. For example, in the bathroom or toilet, you need to remove 25m3/h of air, in a kitchen with a 4-burner stove — 90 m3/h Don’t forget that in most cases we call the kitchen, including the dining room, so for the eating room you need to add at least 1 times the fresh air.
You can find a complete list of rules for organizing air exchange in residential buildings in MGSN 3.01-01. After determining the amount of air to be removed and supplied for each room, it is necessary to make a table of the air balance of the building, in which the total values of supply and exhaust must be equal.
To minimize operating costs, it is allowed to operate the ventilation system not at full strength (in standby mode) in rooms where people are rarely (for example, in guest rooms, billiard rooms, libraries). To do this, the system must be equipped with special automation and throttle valves that regulate the air supply to individual rooms.
Plastic as a material for the ventilation system: advantages and disadvantages
The most common material for air ducts is galvanized steel, but in recent years, plastic is gaining more and more popularity, as it has the following advantages:
- Light weight. For transportation, lifting to the floor and installation of plastic pipes, special devices and hiring workers are not required, it is quite easy to handle everything on your own;
- Corrosion resistance. This property is especially important for rooms with high humidity (bathroom, toilet, laundry room, and so on);
- Surface smoothness. Air moves through the pipes with minimal pressure loss, moreover, over time, the inner walls are less polluted compared to galvanized steel pipes;
- Ease of installation. For the installation of plastic air ducts, much less fixtures are required.
Among the disadvantages of plastic pipes, it is worth noting poor resistance to high temperatures (therefore, it is highly recommended not to install them in a sauna) and a small selection of sizes compared to steel pipes, which can be made to order. However, for a small private house, the line is quite enough, because ventilation from sewer pipes can be installed.
Selection of air ducts and equipment
After calculating the air exchange and selecting the material for the system, it is necessary to select ventilation equipment and pipeline diameters for air distribution throughout the premises. The main parameter at this stage is the pressure loss in the duct. That is, the longer the line, the narrower the pipes and the greater the air speed, the greater the pressure loss, which means that the fan will produce less power. The aerodynamic calculation is rather complicated, however, for small runs, the table below can be used to select the diameter of the vent pipe.
The optimal value of the air velocity in the duct is 3-4 m / s, more — you will hear noise from the system, less — you will need a more powerful fan. After selecting the sections, using another table, the pressure losses along the length are determined, summing up the obtained values, we get a figure, depending on which we select a fan for the system.
It is only necessary to sum up the values along the route to the most remote switchgear, the losses on the branches do not play a role. Please note that each element of the system (distribution grill, silencer, heater) also loses pressure, the specific value is indicated in the parameters of the selected equipment.
In order for the designed ventilation in a private house (or in a country house) made of plastic pipes to be as efficient and least expensive as possible, follow the rules below:
- The exhaust pipe must be raised above the ridge of the building to prevent the suction of polluted air into the windows of the upper floors;
- To ventilate the under-roof space, it is necessary to install an aerator;
- Check valves should be installed in the branches leading to the kitchen and bathrooms so that extraneous odors do not spread around the house when the system is not functioning;
- The number of turns must be kept to a minimum to reduce drag;
- Use round pipes whenever possible.
When planning the location of the inlet, the height of the chimneys must be taken into account. The ideal option is the location of the supply equipment on the first floor of the building, but that the supply opening is at least a meter away from the ground.
Installation of plastic pipes
Pipes for the ventilation system of a private house are mounted according to the following scheme:
- Drilling holes for pipes to pass through walls and floor slabs.
- Cutting the ducts to the required length.
- Remove uneven edges with sandpaper.
- Threading pipes into connecting elements (transitions from one section to another, bends, tees, and so on) using sealant.
- Attaching air ducts to walls and ceilings with clamps and brackets.
- Installation of equipment and distribution devices.
- Leak test by connecting a fan.
Important! A throttle valve must be installed on the supply branch of the system to prevent drafts when the system is turned off.