Heat recovery in a house or industrial premises allows you to save energy resources spent on the use of a ventilation system. This mechanism is especially useful in conditions of limited heat resource or the inability to provide sufficiently effective heating of the room.
Description and principle of operation of the heat recuperator
The literal meaning of the term “recovery” is “return back”. Heat recovery in ventilation systems involves the transfer of part of it from the exhaust air masses removed from the room to the cold air coming from the street. The latter as a result is able to warm up to 2/3 of the difference between the internal and external temperature. Using an air recuperator reduces the cost of heating and ventilation.
Industrial devices of this type operate on electricity. However, they can be left on around the clock.
The principle of operation of the recuperator is implemented as follows: air masses from the street are sent to the served building through a ventilation duct. In the ventilation unit, they are cleaned from dust, heated and go into the room. The stale air from toilets, utility rooms, from the kitchen passes into the apparatus and gives off heat to the masses coming from outside. Used air is discharged into the external environment after it is cooled.
The devices are equipped with control panels, through which you can perform the following actions:
- adjust the temperature of the air masses entering the room;
- adjust the frequency of filter changes;
- control fan speed.
You can set a mode in which on certain days or times of the day the air exchange is not so intense. This move helps save energy.
Varieties of recuperators for ventilation
The types of recuperators found on sale vary in design. This determines the effectiveness of the device, and may also impose restrictions on the area of use.
Lamellar
Models are very popular due to their affordable price and high performance. This is facilitated by a simple installation. Often they are purchased for cottage buildings, commercial premises. Air recuperation in them is carried out during passage through a structure from a large number of plates. The structure of such devices predisposes to the accumulation of condensed moisture, therefore, they are often equipped with shutter devices that prevent the fan from sucking in and directing water to the ventilation duct. In winter, there is a risk of ice floes.
Rotary
The heat recovery unit is equipped with a spinning rotor. It transfers heat between the supply and exhaust paths. Speed determines recovery performance. The devices have high efficiency (up to 90%) and the corresponding cost. Used in large rooms for industrial and other purposes. The openness of the design increases the likelihood of odors moving from the exhaust air to the incoming one.
With intermediate heat carrier
Typically, the role of a liquid coolant circulating between a pair of heat exchange elements is simple water. Sometimes a solution of ethylene glycol is used. One exchanger is mounted in the supply duct, the second - in the outlet. The liquid is heated by the exhaust air and gives off heat to the supply air. Due to the closed design, dirt and odors from the exhaust duct do not enter the supply air.Such a recuperator has a low efficiency (50-60%), therefore they put it in those places where it is important to exclude mixing of flows. Usually this implies a high pollution of the exhaust air or its saturation with harmful compounds.
Chamber
The design is based on a camera divided into 2 zones by a partition. The exhaust air heats one of the parts. The partition changes the direction of the air flow so that the supply mass is heated from the warm inner surface of the chamber. The device is quite effective (up to 80%), but there is a possibility of odors and dirt getting into the stream entering the room.
Heat pipes
At the heart of this design are tubes filled with freon. The spent masses, going through the device, transfer their heat to the pipes, the gas evaporates. With the passage of air coming from the street through the system, steam condensation occurs with the transition of the substance into liquid form. The efficiency of such a regenerative device is low (up to 70%).
Advantages and disadvantages
The main advantage of these devices is the ability to regulate the intake and departure of air masses and their ratio. Thanks to the heating of the exhaust gas flow from the street, the amount of energy spent by the heating devices to achieve the desired room temperature is reduced. This saves on electricity. This applies to the use of the device in an industrial premises, the purchase of an inexpensive model for a home or making it yourself. Acquiring an expensive recuperator for the home is economically unprofitable.
The mechanism allows to reduce heat loss while maintaining the flow of fresh air into the room. It provides a combination of a constant flow of oxygen and maintaining an optimal temperature. When the street is warm enough, the user can not connect the heaters, which additionally helps to save electricity. This ensures the effective removal of unpleasant odors and impurities contained in the air. The advantages include the small size of the installation and ease of installation. They are available in a large number of options - for placement in the bathroom, embedding in a niche, etc.
The disadvantages include high prices for devices (from 20 to 100 or more thousand rubles), which encourages craftsmen to create plate-type devices with their own hands. In addition, models with an open design may not cope effectively with the removal of odors and contaminants from the exhaust air masses.
If the device becomes unusable, the complexity of the repair depends on which unit was damaged. Troubleshooting mechanical problems is usually simpler and more affordable than complex electronics failures.
Choosing a unit with a recuperator
The system is designed based on the purpose of the premises served, its area and internal structure, as well as the estimated number of people who will live or work there. The duct network is mounted, taking into account the pressure losses present in the ventilation system.
One of the important factors is the efficiency of the recuperator. It depends on the internal structure of the device, on the material and type of heat exchanger:
- High efficiency is distinguished by rotor variants equipped with automation of control by sensors. However, in winter such devices may ice up.
- When using an exchanger from paper, the efficiency is average (60-70%), but such models are resistant to freezing.
- For aluminum variants, the design of which is icing-free, additional electricity has to be spent to prevent it.
In any case, the efficiency of devices at very low temperatures (less than -10ºС) tends to decrease. It also affects high humidity.
It is necessary to pay attention to the thickness of the walls of the device and the raw materials from which the cold bridges are made. The thinner the walls, the more they are subject to winter freezing. On sale are often found models with a parameter of 3 cm, which is insufficient for winter conditions. When purchasing such a device, it must be equipped with an additional insulating layer when the temperature outside the window drops below zero. The same applies to models with an aluminum casing.
Another important parameter is the free pressure of the ventilation devices. The figure of the indicator is not considered by itself, but in relation to the parameters of the system (in particular, the pressure) in which the device is to be operated. The power of the device and its ability to provide the necessary volume of hourly air flow are also important. A plus is high-quality automation with a versatile set of options, which provides the ability to adjust parameters based on sensor readings. In this case, the user does not need to constantly monitor temperature indicators and quickly configure the system in accordance with them.
Popular manufacturers
Low-cost compact installations include Danish Nova-300 Sensitive Shuft. The company's products, presented on the Russian market, are adapted to the climatic conditions of the country and can work without pre-heating at temperatures above -10 ° C. The device has a highly efficient recuperator (declared efficiency - 94%) and high-quality filters that trap dust particles and unpleasant odors. The productivity of the model is not very large (up to 200 cubic meters per hour), but it is quite suitable for servicing a home or office space. The heating element is made of ceramic. The fan can work in 3 modes. The installation has a WiFi module, thanks to which the user can configure it using a smartphone. There is the possibility of regulating the temperature parameters and linking the operation of the device to certain time intervals.
Inexpensive models for apartments and offices are produced by the company Electrolux. One such device is the EPVS-200. It works almost silently. The efficiency of the recovery device is 85%, there is a frost protection unit and 2 fan operation modes. The system allows you to maintain air humidity at a given level. The option of remote control and self-diagnosis of malfunctions is implemented. The disadvantage is the lack of an air cooler.
Italian company Royal clima produces models of the middle price category with high productivity (330 cubic meters per hour). The RCS 350 is designed for pendant mounting. It works silently, equipped with a plate heat exchanger with an efficiency of 90%. Functional parameters can be set remotely using the remote control. The recuperator works effectively at temperatures up to -20ºС.
Democratic price (less than 15 thousand rubles.) Models differ from a German company Winzel and Ukrainian Vents. Unlike previous devices, these products are of decentralized type. Both of them are able to work at low temperatures without freezing, have a high efficiency of the recuperator (88 and 90%, respectively), but they have low ventilation performance (50 cubic meters per hour). Suitable for installation in an apartment or a small private house.
Decentralized plants with a plate exchanger are also produced by Royal Clima. They are equipped with additional functions (air ionization, additional carbon filter), but they are notable for their high price. Hourly productivity reaches 150 cubic meters. Management is carried out through the remote control.
The use of heat recuperators allows you to save resources on space heating while maintaining the flow of fresh air. The installation must be selected based on the design parameters of the system.
