As part of the project, we decided to answer questions from portal users regarding the selection and installation of recuperators.
Of these installations will be put into operation at our construction site, which determined the topic of this article. Questions regarding the types of ventilation systems and the criteria by which recuperators should be selected will be analyzed with the help of manufacturers - engineers from the TURKOV company.
In this article:
So, why was a supply and exhaust system chosen? To fully understand the issue, let’s consider the types of modern supply and exhaust systems.
Natural impulse ventilation is a system that includes wall and window supply valves(providing fresh air access to the room), as well as a system of exhaust air ducts (removing waste air from toilets, bathrooms and kitchens). Possibility of air exchange if available natural ventilation is ensured by the difference in temperature inside and outside the room.
The advantages of such a system are its simplicity and low cost; the disadvantages include low efficiency and insufficient quality of air exchange. Also, the disadvantages include a large load on the heating system and seasonal instability. For example, in the summer, when the temperature of indoor and outdoor air equalizes, air exchange in the room practically stops. In winter, on the contrary, the system works more efficiently, but this requires additional costs for heating the air coming from the street.
Combined ventilation is a system with forced exhaust and natural air flow. Its disadvantages:
The advantages of the combined system are its relatively low cost and the absence of seasonal problems with draft in the exhaust duct. However, in terms of air exchange and functionality combined system falls far short of full supply and exhaust ventilation.
Classical forced ventilation ensures circulation of air flows in specified modes and volumes. This system is equipped with supply and exhaust air ducts, as well as specialized ventilation equipment capable of maintaining stable air exchange in the room all year round. Such systems have one big disadvantage: they are very energy-consuming when used in winter. This is explained by the fact that the cold air flow from the street must be constantly heated to a comfortable room temperature.
Forced ventilation with a recuperator is the most advanced system capable of circulating air flows in specified modes and volumes. Its operation involves minimal energy consumption. After all, the flow from the street is first heated by the recuperator (due to the heat contained in the exhaust air), and then the air is additionally heated to a temperature comfortable for humans. In many developed countries, such a technical solution has already become a construction standard enshrined in legislation.
Taking into account the growing requirements for the comfort of residential premises, it is advisable to equip any new house not just with standard ventilation ducts, but with a multifunctional and economical forced ventilation system. The recuperator-based system provides a supply of clean air from comfortable temperature and at the same time removes waste air masses outside the room. At the same time, heat (and sometimes moisture) is selected and transferred from the exhaust flow to the supply flow.
Firstly, unlike classical ventilation, the recuperator allows you to significantly save on equipment operation. Secondly, the cost of a recuperator is not much higher than the cost of a classic one. ventilation equipment. Thirdly, during operation of the recuperator, 80% of the heat of the exhaust air is returned back to the supply air, which significantly reduces the cost of heating it.
On hot summer days, heat exchange occurs in the opposite direction, which also allows you to save on air conditioning. Simultaneously with the transfer of heat in the heat exchanger, moisture is transferred from the exhaust air to the supply air. In physics there is such a thing as “dew point”. This is the moment when the relative humidity of the air reaches 100% and the moisture changes from a gaseous state to a liquid state (condensation). Condensation appears on the surface of the recuperator, and the lower the temperature outside, the greater the likelihood of condensation forming on the recuperator. Since the enthalpy recuperator allows moisture to be transferred from the exhaust air to the supply air, the “dew point” shifts to a zone of very low temperatures. The recuperator allows you to maintain a higher relative humidity of the supply air (compared to classical ventilation), and also significantly increases frost resistance and eliminates the need for condensate removal.
The presence of the above functions fully explains the choice of such an air handling unit.
Introducing functional diagram installations.
Where:
M1 and M2 – supply and exhaust fans;
D (1, 2, 3) – temperature sensors;
K (1, 2, 3) – heat exchangers;
F (1, 2) – air filters.
The first thing you need to pay attention to when choosing a model of a supply and exhaust heat exchanger is the wording used by the manufacturer or seller of the equipment. We often hear the following: “efficiency up to 99%”, “efficiency up to 100%”, “operation down to -50ºС” - all these phrases are nothing more than a manifestation of a marketing strategy with a simultaneous attempt to mislead the buyer. As experience in operating recuperators in the Russian climate has shown, metal recuperators operate stably when the temperature drops to -10ºС. Then the process of reducing efficiency begins due to freezing of the recuperator. To prevent this from happening, many manufacturers use additional heating sources (electrical preheating).
The second thing you need to pay attention to is the thickness of the equipment casing, the material from which the casing frame is made and the presence of cold bridges in the casing. Let's return to the experience of use again: let's look at the features of the 30mm thick case. This housing cannot withstand a drop in street temperature to -5ºС and must be additionally insulated. If the case is made of an aluminum frame, then additional insulation will also become an integral part of it. After all, aluminum is one large bridge of cold, “spreading” along the entire perimeter of the case.
Third: one of common mistakes when choosing a recuperator, the buyer does not take into account the free pressure of the fans. He sees only the magic figure - 500 m³ and the price - 50 thousand rubles, and the buyer learns that the fan has a pressure of 0 Pa at 500 m³ only after finishing the house renovation, that is, during the operation of the already installed equipment.
The fourth selection criterion is the presence of automation and the ability to connect optional components to it. Automation can significantly reduce operating costs and achieve maximum comfort when operating equipment.
As for performance: the main calculation parameter is the volume of air that should enter the room within one hour. In accordance with sanitary standards, this volume should be equal to 60 m³ per adult or one times per hour of the total cubic capacity of the premises served (living room, kitchen, bedrooms). When choosing a recuperator, you need to look not only at the performance of the installation, but also at the pressure of the fans that pump your ventilation network around the house.
It is better to entrust the calculation of the required productivity to specialists. Indeed, in case of an error, replacing the recuperator will require significant financial costs.
When calculating and choosing an installation, to obtain more accurate information, you will have to read specialized literature and forums, call manufacturers and suppliers of equipment (the topic is very broad). It's always better to turn to specialists. And for those people who are not deterred by this advice, it is still recommended to confirm the correct choice with the equipment manufacturer or distributor.
It cannot be said that any recuperator is worse or better; each type of recuperator has its own strengths and areas of application. The efficiency of a rotary and plate recuperator is absolutely the same, since the efficiency depends on two parameters: the area of the heat exchange surface of the recuperator and the direction of the air flow in the recuperator.
The design of the rotary heat exchanger allows partial mixing of the supply and exhaust flows, since the air flow insulator in it is a brush. Fine bristle brush, in itself, is a poor insulator between air flows, and a slight imbalance in the system leads to an even greater flow of exhaust air into the supply channel. Also, the weak link in a rotary recuperator is the engine and the belt that spins the rotor: additional moving parts reduce the overall reliability of the equipment and also increase energy costs for recuperation. The rotary heat exchanger can only be installed in one position, which also reduces the possibility of its use at home. The main objects for the use of rotary recuperators are shopping centers, hypermarkets and others public buildings with a large area where air flow only benefits the building owners.
We present a diagram of the operation of a rotary recuperator.
Plate recuperators, unlike rotary devices, are not so massive, but at the same time they are easy to install and reliable in operation. Among plate recuperators, membrane-type equipment deserves special attention. Special polymer membrane, built into the recuperator, returns moisture from the exhaust air to the supply air. At the same time, it prevents the formation of condensation, as well as the formation of ice inside the device (during its operation at low temperatures).
Based on plate recuperators, it is possible to build multi-stage recuperation, which allows you to avoid direct contact of the coldest air flow (coming from the street) with the warmest (coming from the house). And in conjunction with an enthalpy recuperator, this technology allows you to avoid freezing of the recuperator. A smooth decrease in the temperature of the exhaust air and a gradual increase in the temperature of the supply air inside the recuperator make the device resistant even to temperatures in the far north. As practice shows, such equipment works successfully in the most severe climatic conditions, for example, Yakutsk.
PeterPro FORUMHOUSE user
Used in plate heat exchangers different material. Plastic and metal heat exchangers freeze. Membrane heat exchangers use a thin film that only allows moisture to pass through. There are two or three heat exchangers in such an installation, depending on the model.
Efficiency is one of the main characteristics of a recuperator, and special attention should be paid to its value before purchasing a unit.
It is important to choose a recuperator for your home that has sensitive and reliable automation. After all, there is nothing worse than equipment that is constantly involved in work and requires attention with enviable regularity. Modern automation of recuperators opens up additional opportunities for users:
A design features allow you to equip the device with additional options and systems:
This also includes an improved filtration system.
When choosing equipment, you need to consider the air handling unit as a climate complex that will maintain air flow, as well as temperature and humidity (if necessary) in a given mode. Installing additional heaters, coolers, VAV valves, humidifiers or dehumidifiers is already becoming a vital necessity today.
Shuvalov Dmitry
If the recuperator itself cannot maintain the required supply air temperature, then the device should be retrofitted with a heater of appropriate power. On average, if the calculated temperature in the channel does not fall below +14...+15°C, then the heater does not need to be installed. My opinion is this: it is better not to turn on the heater if it is not needed, than when it is needed, there will be nothing to turn on.
The above systems and devices make it possible to minimize human participation in system management and improve the quality of the microclimate in the house. A modern climate system is capable of constantly monitoring the performance of all components of optional equipment and, if necessary, warning the user about problems in the operation of the system and changes in the microclimate in the room. When using a VAV system, the operating costs of the installation are significantly reduced by temporarily and/or partially disconnecting individual rooms from the ventilation system.
Currently, there are models of recuperators that are capable of connecting to individual “” systems using the ModBus or KNX protocols. Such devices are ideal for connoisseurs of advanced and modern functionality.
When choosing a recuperator, it is important to pay attention to the noise level it creates during operation. This indicator depends on the material from which the device case is made, on the thickness of the case, on the power of the fans and on other parameters.
According to the type of installation, recuperators can be suspended (mounted on the ceiling) or floor-mounted (installed on a flat horizontal surface or hung on a wall). Exits for ventilation ducts can be either on both sides (“through” layout) or on one side (“vertical” layout). Which recuperator you need depends on the specific parameters of your ventilation system and on where exactly the supply and exhaust equipment will be installed.
Installation recommendations mainly concern the premises in which the recuperator should be installed. First of all, boiler rooms are used for installation (if we're talking about about private households). Recuperators are also installed in basements, attics and other technical rooms.
If this does not conflict with the requirements technical documentation, then the installation can be installed in any unheated room, while the distribution of ventilation ducts, if possible, should be installed in rooms with heating.
Ventilation ducts passing through unheated rooms (as well as outdoors) should be made as insulated as possible. Air ducts running from the equipment to the street (supply and exhaust) are also necessarily insulated. It is also necessary to thermally insulate the passages of air ducts through external walls.
Considering the noise the equipment can make during operation, it is best to place it away from bedrooms and other living rooms.
Regarding the placement of the recuperator in the apartment: best place there will be a balcony or some technical room for it.
If this is not possible, you can allocate free space in the dressing room for installing a recuperator.
Be that as it may, the location of the installation largely depends on the layout of the apartment or house, on the layout and location of the ventilation network and on the dimensions of the device.
It is recommended to pay special attention to such an element as the crossbar. Already existing bolts can become big problem when laying a ventilation network. You can only get around this element through a technical room or a built-in closet, which is not always possible. Therefore, you should think about the ventilation design even when designing a house, having previously provided for the presence of passage windows in the crossbar. The same recommendation applies to roof passages.
If a recuperator is built into the ventilation system, then it is recommended to equip common areas (corridors, hallways, etc.), as well as technical rooms, with exhaust ducts. In this case, fresh air should be supplied in living rooms: bedrooms, offices, halls, etc.
However, there are situations in which connecting bathrooms to ventilation system with a recuperator is allowed (please note that we are talking specifically about rooms, and not about hoods located in these rooms). But due to the cold Russian climate, such a connection requires observing quite a lot of nuances, which is not always possible. In any case, if you have any questions about the possibility of such a connection, you need to contact the relevant specialists. It is strongly not recommended to connect bathrooms to the recuperator yourself.
DiJo User FORUMHOUSE
The air intake should be done from the side from which the wind blows less (so less dust will enter).
The supply air intake point should be located at a sufficient distance from exhaust openings, chimneys and other sources of pollution.
Installation and maintenance work on the recuperator should be carried out in accordance with the manufacturer's requirements. To be completed installation work It is advisable to involve specialists familiar with all the nuances of operating such equipment.
Supply and exhaust ventilation - This is an integrated approach to the problem of ventilation.
Supply and exhaust units provide an active flow of fresh air into the room and removal of exhaust air masses from the room. Recuperators are becoming increasingly popular, the advantage of which is the supply of fresh air heated to room temperature, with minimal annual energy consumption.
Recuperators return up to 95% of the heat back to the room, creating virtually no additional energy costs. Thus, recuperators are the most economical type of ventilation unit for supplying warm air to the room. This is achieved by retaining heat from exhaust room air on heat exchangers.
The latest models of recuperators combine the functions of supply and exhaust ventilation and fine air purification from allergens, are equipped with carbon dioxide sensors, specially designed heat exchangers to maintain optimal humidity conditions, and the ability to control from a smartphone.
Installing a recuperator effectively helps to cope with stuffiness, control room humidity, mold and dampness in the house, and condensation on plastic windows.
We are an official dealer of leading manufacturers and can provide a best price guarantee. From us you can choose and buy any model of recuperator with delivery throughout Moscow and Russia.
Supply and exhaust ventilation units with heat recovery appeared relatively recently, but quickly gained popularity and became a fairly popular system. The devices are capable of fully ventilating the room during the cold period, while maintaining the optimal temperature regime of the incoming air.
When using supply and exhaust ventilation in the autumn-winter period, the question of preserving heat in the room often arises. The flow of cold air coming from the ventilation rushes to the floor and contributes to the creation of an unfavorable microclimate. The most common way to solve this problem is to install a heater that heats the flow of cold street air before supplying it to the room. However this method is quite energy-consuming and does not prevent heat loss in the room.
The best solution to the problem is to equip the ventilation system with a recuperator. The recuperator is a device in which the air outflow and supply channels are located in close proximity to each other. The recuperation unit allows partial transfer of heat from the air leaving the room to the incoming air. Thanks to the technology of heat exchange between multidirectional air flows, it is possible to save up to 90% of electricity; in addition, in the summer, the device can be used to cool incoming air masses.
The heat recuperator consists of a housing, which is covered with heat and sound insulating materials and is made of sheet steel. The device body is quite durable and can withstand weight and vibration loads. The housing has inflow and outflow openings, and air movement through the device is ensured by two fans, usually of an axial or centrifugal type. The need to install them is due to a significant slowdown in natural air circulation, which is caused by the high aerodynamic resistance of the recuperator. To prevent the suction of fallen leaves, small birds or mechanical debris, an air intake grille is installed on the inlet located on the street side. The same opening, but on the room side, is also equipped with a grille or diffuser that evenly distributes air flows. When installing branched systems, air ducts are mounted to the openings.
In addition, the inlets of both flows are equipped with fine filters that protect the system from dust and grease droplets. This protects the heat exchanger channels from clogging and significantly extends the service life of the equipment. However, the installation of filters is complicated by the need to constantly monitor their condition, clean them, and, if necessary, replace them. Otherwise, a clogged filter will act as a natural barrier to air flow, causing resistance to increase and the fan to break.
According to the type of design, recuperator filters can be dry, wet or electrostatic. The choice of the right model depends on the power of the device, the physical properties and chemical composition of the exhaust air, as well as the personal preferences of the buyer.
In addition to fans and filters, recuperators include heating elements, which can be water or electric.
Each heater is equipped with a temperature relay and is capable of automatically turning on if the heat leaving the house cannot cope with heating the incoming air. The power of the heaters is selected in strict accordance with the volume of the room and the operating performance of the ventilation system. However, in some devices, heating elements only protect the heat exchanger from freezing and do not affect the temperature of the incoming air. Water heater elements are more economical. This is explained by the fact that the coolant that moves along the copper coil enters it from the heating system of the house. The coil heats the plates, which, in turn, give off heat to the air flow. The water heater regulation system is represented by a three-way valve that opens and closes the water supply, a throttle valve that reduces or increases its speed, and mixing unit
regulating temperature. Water heaters are installed in an air duct system with a rectangular or square cross-section. Electric heaters are often installed on air ducts with round , and their heating element is a spiral. For correct and efficient work
spiral heater, the air flow speed should be greater than or equal to 2 m/s, the air temperature should be 0-30 degrees, and the humidity of the passing masses should not exceed 80%. All electric heaters are equipped with an operation timer and a thermal relay that turns off the device if it overheats. In addition to the standard set of elements, at the request of the consumer, air ionizers and humidifiers are installed in recuperators, and the most modern models are equipped with electronic unit control and programming function of the operating mode, depending on external and internal conditions. The instrument panels are aesthetically pleasing appearance
In order to better understand how the recuperative system works, you should refer to the translation of the word “recuperator”. Literally it means “return of used”, in this context – heat exchange. In ventilation systems, the recuperator takes heat from the air leaving the room and transfers it to incoming air flows. The temperature difference between multidirectional air jets can reach 50 degrees. In the summer, the device works in reverse and cools the air coming from the street to the temperature of the outlet. On average, the efficiency of devices is 65%, which allows rational use of energy resources and significant savings on electricity.
In practice, heat exchange in a recuperator looks like this: Forced ventilation drives an excess volume of air into the room, as a result of which contaminated masses are forced to leave the room through the exhaust duct. Coming out warm air passes through the heat exchanger, heating the walls of the structure. At the same time, a flow of cold air moves towards it, which takes away the heat received by the heat exchanger without mixing with the exhaust flows.
However, cooling the air leaving the room leads to the formation of condensation. If the fans work well, imparting high speed to the air masses, the condensate does not have time to fall onto the walls of the device and goes out into the street along with the air stream. But if the air speed was not high enough, then water begins to accumulate inside the device. For these purposes, the design of the recuperator includes a tray, which is located at a slight inclination towards the drain hole.
Through the drain hole, water enters a closed tank, which is installed on the side of the room. This is dictated by the fact that accumulated water can freeze the outflow channels and the condensate will have nowhere to drain. It is not recommended to use collected water for humidifiers: the liquid may contain a large number of pathogenic microorganisms, and therefore must be poured into the sewer system.
However, if ice still forms from condensation, it is recommended to install additional equipment– bypass. This device is made in the form of a bypass channel through which supply air will enter the room. As a result, the heat exchanger does not heat the incoming flows, but spends its heat exclusively on melting the ice. The incoming air, in turn, is heated by a heater, which turns on synchronously with the bypass. After all the ice has been melted and the water has been discharged into the storage tank, the bypass is turned off and the recuperator begins to operate normally.
In addition to installing a bypass, hygroscopic cellulose is used to combat icing. The material is located in special cassettes and absorbs moisture before it has time to fall into condensation. Moisture vapor passes through the cellulose layer and returns to the room with the incoming flow. The advantages of such devices are simple installation, the optional installation of a condensate collector and storage tank. In addition, the operating efficiency of cellulose recuperator cassettes does not depend on external conditions, and the efficiency is more than 80%. The disadvantages include the inability to use in rooms with excessive humidity and the high cost of some models.
The modern ventilation equipment market offers a wide selection of recuperators different types, differing from each other both in design and in the method of heat exchange between flows.
Thanks to the wide variety of recuperators presented to consumers, choose the desired model won't be difficult. Moreover, each type of device has its own narrow specialization and recommended installation location. So, when purchasing a device for an apartment or private house, it is better to choose a classic plate model with aluminum plates. Such devices do not require maintenance, do not require regular maintenance and have a long service life.
This model is perfect for use in an apartment building. This is due to the low noise level during its operation and compact dimensions. Tubular standard models have also proven themselves well for private use: they are small in size and do not buzz. However, the cost of such recuperators is slightly higher than the cost of plate products, so the choice of device depends on the financial capabilities and personal preferences of the owners.
When choosing a model for a production workshop, non-food warehouse or underground parking lot, you should choose rotary devices. Such devices have great power and high performance, which is one of the main criteria for working on large areas. Recuperators with intermediate coolant have also proven themselves well, but due to their low efficiency they are not as in demand as drum units.
An important factor when choosing a device is its price. Yes, the most budget options plate heat exchangers can be purchased for 27,000 rubles, while a powerful rotary heat recovery unit with additional fans and a built-in filtration system will cost about 250,000 rubles.
In order not to make a mistake when choosing a recuperator, you should calculate the efficiency and operating efficiency of the device. To calculate the efficiency, use the following formula: K = (Tp - Tn) / (Tv - Tn), where Tp denotes the temperature of the incoming flow, Tn is the street temperature, and Tv is the room temperature. Next, you need to compare your value with the maximum possible efficiency indicator of the purchased device. Typically this value is indicated in the model’s technical data sheet or other accompanying documentation. However, when comparing the desired efficiency and that indicated in the passport, you should remember that in fact this coefficient will be slightly lower than stated in the document.
Knowing the efficiency of a particular model, you can calculate its effectiveness. This can be done using the following formula: E (W) = 0.36xPxKx (Tv - Tn), where P will denote air flow and is measured in m3/h. After all the calculations have been made, you should compare the costs of purchasing a recuperator with its efficiency, converted into monetary equivalent. If the purchase justifies itself, you can safely purchase the device. Otherwise, you should think about alternative methods heating the incoming air or installing a number of simpler devices.
When independently designing a device, it should be taken into account that counterflow devices have the maximum heat transfer efficiency. They are followed by cross-flow ducts, and in last place are unidirectional ducts. In addition, how intense the heat exchange will be directly depends on the quality of the material, the thickness of the dividing partitions, and also on how long the air masses will remain inside the device.
Assembly and installation of the recovery unit can be carried out independently. The most simple view homemade device is a coaxial recuperator. To make it, take a two-meter plastic sewer pipe with a cross-section of 16 cm and an aluminum air corrugation 4 m long, the diameter of which should be 100 mm. At the ends big pipes put on adapter-splitters, with the help of which the device will be connected to the air duct, and put the corrugation inside, twisting it in a spiral. The recuperator is connected to the ventilation system in such a way that warm air is driven through the corrugation, and cold air goes through a plastic pipe.
As a result of this design, mixing of flows does not occur, and the street air has time to warm up while moving inside the pipe. To improve the performance of the device, you can combine it with a ground heat exchanger. During testing, such a recuperator gives good results. So, with an external temperature of -7 degrees and an internal temperature of 24 degrees, the productivity of the device was about 270 cubic meters per hour, and the temperature of the incoming air corresponded to 19 degrees. average cost homemade model
– 5 thousand rubles. At self-production When installing a recuperator, it should be remembered that the longer the heat exchanger is, the higher the efficiency of the installation. That's why It is recommended to assemble the recuperator from four sections of 2 m each, having carried out preliminary thermal insulation of all pipes. The problem of condensate drainage can be solved by installing a fitting for draining water, and placing the device itself at a slightly inclined angle.
