Until recently, supply and exhaust ventilation with an air recuperator was used quite rarely in Russia, until experts came to the conclusion that such a system was a necessity. The operation of ventilation is based on the principle of recovery. This is the name of the process in which part of the heat is returned from exhaust air. Leaving the room, warm air partially heats the oncoming cold flow in the heat exchanger. Thus, completely “exhausted” air goes outside, and not only fresh, but also already heated air enters the room.
Why is it high time to abandon the old type of exhaust ventilation?
Why is traditional natural exhaust ventilation, which has been installed in private houses, apartments and buildings for many years, no longer effective? The fact is that in this case, through frames, doorways and cracks, there should be a continuous penetration of air into the room, but if sealed plastic double-glazed windows are installed, the air flow is greatly reduced and, as a result, the natural exhaust ventilation system ceases to function normally.
In order for the air temperature in the premises to be comfortable, in winter the air needs to be heated, for which in our country, homeowners spend huge amounts of money, because... cold weather in our country lasts 5-6 months. And although the heating season is shorter, huge resources are still spent on heating the supply air. However, the disadvantages of natural exhaust ventilation do not end there. Not only cold but also dirty air enters the room from the street, and drafts also occur periodically. There is no way to control the volume of these air flows. It turns out that due to unbalanced ventilation, a lot of money is literally thrown into the wind, because people are forced to pay for heating the air, which flies down the chimney in a couple of minutes. Since energy prices are rising year after year, it is not surprising that the question of reducing heating costs sooner or later arises for every thrifty person who does not want to “heat the street” at their own expense.
How to save heat in your home
To save heat in the ventilation system - heating the cold supply air due to the warm air removed from the room, special recuperator units are designed. A cassette is built into supply and exhaust ventilation units to ensure air heat exchange. Coming out through it, the exhaust air transfers heat to the walls of the heat exchanger, while the cold air flowing into the room is heated by the walls. This principle is the basis for the operation of plate and rotary heat exchangers, which have currently gained popularity in the market of ventilation units.
Are there any disadvantages to plate recuperators?
In devices of this type, air flows are, as it were, cut by plates. These supply and exhaust systems, in addition to many advantages, which will be discussed later, also have one drawback: on the side where the exhaust air exits, ice forms on the plates. The problem is explained simply: as a result of the fact that the heat exchange plate and the exhaust air have different temperatures, condensation forms, which, in fact, turns into ice. Air begins to pass through frozen plates with enormous resistance, and ventilation performance drops sharply, and the recovery process practically stops until the plates are completely thawed.
The process can be compared to taking a bottle of lemonade out of the freezer. The glass would instantly be covered first with a white film, and then with drops of water. Is it possible to combat the problem of recuperator freezing? Experts found a way out by installing a special bypass valve in ventilation systems with recovery. As soon as the plates are covered with a layer of ice, the bypass opens, and the supply air for some time bypasses the recuperator cassette, entering the room with virtually no heating. At the same time, the recuperator plates are defrosted quite quickly due to the removed exhaust air, and the resulting water is collected in the drainage bath. The bath is connected to a drainage system that goes into the sewer system, and all condensate is drained there. The recuperator begins to work effectively again, and air exchange is restored.
When the cassette defrosts, the valve closes again, however, there is one “but” here. When air does not enter the heat exchanger and bypasses it, energy savings are minimized. This is due to the fact that the supply air, as a rule, in addition to the heat exchanger plates, heats up the built-in air heater - exactly the same as that found in simple air supply units, but with significantly less power. How to deal with this? Is it possible to deal with ice without losing money?
Supply and exhaust ventilation units with heat recovery
Manufacturers of recuperators have found a solution to this serious problem. Thanks to the invention of new technology, the moisture that settles on the walls of the heat exchanger on the outgoing air side begins to be absorbed into them and moves to the supply air side - moistening it. Thus, almost all the moisture in the removed air gets back into the room. What makes this process possible? Engineers achieved this effect by creating cassettes made of hygroscopic cellulose. In addition, many hygroscopic celluloses do not have bypasses and do not connect to the drainage system with the bathtub and plumbing. All moisture is utilized by air currents, and it remains almost entirely in the room. So, using a cellulose heat exchanger in the recuperator, you no longer need to use a bypass and direct air bypassing the recuperator plates.
As a result, the efficiency of the recuperator was increased to 90%! This means that the supply air from the street will be 90% heated by the exhaust air. At the same time, recuperators can operate without problems even in cold weather, down to -30 degrees Celsius. Such installations are perfect for residential premises, apartments, country houses and cottages, preserving and maintaining the necessary humidity and air exchange in winter and summer, they create and maintain the necessary indoor microclimate all year round, while saving a lot of money. However, it should be remembered that recuperators with cellulose heat exchangers, like all others, are capable of freezing, which over time can lead to failure of the heat exchange cassette. In order to completely eliminate the possibility of freezing, it is necessary to install frost protection. Also, with all their positive qualities, recuperators with a paper heat exchanger cannot be used for rooms with a high moisture content, in particular for. For wet rooms, including swimming pools, it is necessary to use supply and exhaust ventilation units with an aluminum plate heat exchanger.
Diagram and operating principle of a supply and exhaust ventilation system with a recuperator
Let's assume that it is winter outside and the air temperature outside the window is -23 0 C. When the air handling unit is turned on, street air is sucked in by the unit using a built-in fan, passes through the filter and hits the heat exchange cassette. Passing through it, it heats up to +14 0 C. As we see, in winter cold, the installation is not able to completely warm the air to room temperature, although for many, such heating may be sufficient, so after the recuperator, the supply air can go directly to room, or if there is a so-called “air reheat” in the recuperator, passing through it, the air is heated to +20 0 C and only fully heated air enters the room. The reheater is a low-power electric or water heater with a power of 1-2 kW, which can, if necessary, turn on at low outside temperatures and heat the air to a comfortable room temperature. In the configurations of recuperators from various manufacturers, as a rule, it is possible to choose a water or electric reheater. On the contrary, room air with a temperature of +18 0 C (+20 0 C), sucked from the room by a fan built into the installation, passing through a heat exchange cassette, is cooled by the supply air and goes outside from the recuperator, having a temperature of -15 0 C.
What will the air temperature be after the recuperator in winter and summer?
There is a fairly simple way to calculate for yourself what temperature the air will enter the room after the recuperator. How effectively will the supply air be heated and will it be heated at all? What will happen to the air in the recuperator in the summer?
Winter
The picture shows that the street air is 0 0 C, the efficiency of the recuperator is 77%, while the temperature of the air entering the room is 15.4 0 C. How much will the air warm up if the temperature outside is, for example, -20 0 C? There is a formula for calculating the supply air for a recuperator depending on its efficiency, outdoor and indoor air temperature:
t (after the recuperator)=(t (indoors)-t (outdoors))xK (recuperator efficiency)+t (outdoors)
For our example, it turns out: 15.4 0 C = (20 0 C - 0 0 C)x77% + 0 0 C If the temperature outside the window is -20 0 C, in the room +20 0 C, the efficiency of the recuperator is 77%, then the air temperature after the recuperator it will be: t=((20-(-20))x77%-20=10.8 0 C. But this is, of course, a theoretical calculation, in practice the temperature will be slightly lower, about +8 0 C.
Summer
The air temperature after the recuperator in summer is calculated similarly:
t (after the recuperator)=t (outdoors)+(t (indoors)-t (outdoors))xK (recuperator efficiency)
For our example it turns out: 24.2 0 С=35 0 С+(21 0 С-35 0 С)х77%
Diagram and operating principle of a supply and exhaust ventilation system with a rotary heat exchanger
The principle of operation of a rotary recuperator is based on the exchange of heat between the incoming and outgoing air flow in the ventilation system through a rotary aluminum heat exchanger, which, rotating at different speeds, allows this process to be carried out at different intensities.
Which recuperator is better?
Today, recuperators from different manufacturers are available for sale, differing in many respects: operating principle, efficiency, reliability, economy, etc. Let's look at the most popular types of recuperators and compare their advantages and disadvantages.
1. Plate recuperator with aluminum heat exchanger.
The price of such a recuperator is quite low compared to other types of recuperators, which is undoubtedly one of its advantages. The air flows in the device do not mix; they are separated by aluminum foil. One of the disadvantages is the low performance at low temperatures, because... The heat exchanger freezes periodically and must thaw frequently. It is logical that energy costs are rising. It is also not advisable to install them in residential premises, because in winter, during the operation of the recuperator, all moisture is removed from the air in the room and its constant humidification is required. The main advantage of aluminum plate heat exchangers is that they can be installed for ventilation of swimming pools.
2. Plate recuperator with a plastic heat exchanger. The advantages are the same as the previous option, but the efficiency is higher due to the properties of plastic. 
3. Plate recuperator with a cellulose heat exchanger and a single cassette. Despite the fact that the air flows are separated by paper partitions, moisture quietly permeates the walls of the heat exchanger. An important advantage is that the saved heat and moisture are returned to the room. Due to the fact that the heat exchanger is practically not subject to freezing, no time is wasted on defrosting it, and the efficiency of the device increases significantly. If we talk about the disadvantages, they are as follows: recuperators of this type cannot be installed in swimming pools, as well as in any other rooms where there is excess humidity. In addition, the recuperator cannot be used for drying. Very often, like this.
4. Rotary recuperator. It is characterized by high efficiency, but this figure still remains lower than if a plate installation with a double cassette was used. A distinctive feature is low energy consumption. As for the shortcomings, we note the following points, since the oncoming air flows of the rotary heat exchanger are not ideally separated; a small amount of air removed from the room (albeit insignificant) enters the supply air. The device itself is quite expensive, because... complex mechanics are used. Finally, a rotary heat exchanger must be serviced more often than other air handling units and its installation in wet rooms is not advisable.
Recuperators for apartments and country houses
| Mitsubishi Lossney | Electrolux EPVS |
DAIKIN |
Systemair | SHUFT |
What determines the price of a recuperator?
First of all, the price of a recuperator depends on the performance of the entire ventilation system. A professional designer will be able to develop a competent project that satisfies exactly your conditions and requirements, the quality of which will determine not only the efficiency of the entire system, but also your further costs for its maintenance. Of course, you can select the equipment yourself, including air ducts and grilles, but it is advisable that a specialist deal with the identified issues. Developing a project costs extra money, and at first glance, such expenses may seem quite substantial to some, but if you calculate how much money will remain in your budget as a result thanks to competent planning, you will be surprised.
When choosing a recuperator yourself, first of all pay attention to the price and the promised quality. Is the device worth the stated amount? Or will you simply overpay for a new product or brand? The equipment is not cheap and takes several years to pay for itself, so the choice of device should be approached very responsibly.
Be sure to check the availability of product certificates and find out how long the warranty period is valid. Usually the warranty is given not for the recuperator, but for its components. The better the quality of components, assemblies and other components, the more expensive the purchase will be. The reliability of the system is assessed based on the strengths and weaknesses of the product. Nobody offers a natural, ideal option, but finding the best solution for a specific room is quite possible.
How to choose an air handling unit with a recuperator
First of all, ask the seller the following questions:
1. Which company produces the product? What is known about her? How many years on the market? What are the reviews?
2. What is the system performance? These data can be calculated by specialists whom you contact for advice, including specialists from our company. To do this, you must indicate the exact parameters of the premises; it is advisable to provide the layout of an apartment, office, country house, cottage, etc.
3. What will be the resistance of the air duct system to air flow after installing a particular model? These data must also be calculated by designers for each individual case. The calculations take into account all diffusers, duct bends and much more. The model and power of the recuperator are selected taking into account the so-called “operating point” - the ratio of air flow and air duct resistance.
4. What energy consumption class does the recuperator belong to? How much will it cost to maintain the system? How much electricity can you save? You need to know this in order to calculate expenses for the heating season.
5. What is the declared Efficiency Factor of the installation and the real one? The efficiency of recuperators depends on the temperature difference between indoors and outdoors. This indicator is also influenced by such parameters as: type of heat exchange cassette, air humidity, layout of the system as a whole, correct placement of all components, etc.
Let's see how efficiency can be calculated for different types of recuperators.
- If the heat exchanger of a plate recuperator is made of paper, then the efficiency will be, on average, 60-70%. The installation does not freeze, or rather, this happens extremely rarely. If the heat exchanger needs to be defrosted, the system itself reduces the performance of the installation for some time.
- The aluminum plate heat exchanger demonstrates high efficiency - up to 63%. But the recuperator will be less productive. The efficiency here will be 42-45%. This is due to the fact that the heat exchanger must often thaw. If you want to eliminate freezing, you will have to use much more electricity.
- A rotary recuperator shows high efficiency if the rotor speed is regulated by “automation”, guided by the readings of temperature sensors that are installed both indoors and outdoors. Rotary heat exchangers are also susceptible to freezing, as a result of which the efficiency decreases in the same way as plate heat exchangers made of aluminum.
In a house where the ventilation system works well, a person feels very comfortable and gets sick less.
However, to ensure traditional good ventilation, it is necessary to significantly increase heating and air conditioning costs (to maintain normal air temperature in the house).
What is an air recuperator?
Nowadays, they use an improved ventilation system using special devices that can significantly reduce heat loss in winter when exhaust air is exhausted and prevent heat from entering the house in summer when superheated air is supplied from the street. This device is called air recuperator , photo 1.
Photo 1. Air recuperator in the house ventilation system
When properly installed and operated, the air recuperator is capable of “returning” 2/3 of the heat that goes away with the processed air. All recuperators contain filters in their structure to clean the supply air and, depending on the modification, the cleaning quality may be different.
Advantages of using an air recuperator in a general ventilation system:
- Reduces heating and ventilation costs (up to 30...50%).
- Comfortable microclimate in the house, constantly fresh air.
- Reduces dust levels in the house.
- Low operating costs.
- Not a difficult installation.
- The equipment is durable.
Air recuperator design
The air recuperator consists of two chambers that run close to each other, photo 2. Heat exchange occurs between the chambers, which allows the supply air flow to be heated in winter due to the heat of the exhaust flow, and vice versa in summer.
Photo 2. Schematic diagram of the air recuperator operation
Types of recuperators
There are the following types of air recuperators.
- lamellar;
- rotary;
- aquatic;
- roofing
Plate recuperator
Plate recuperator is a housing into which rectangular pipes enter and exit. One side of the two pipes touches, which ensures heat exchange between them. Inside the pipes there are galvanized plates that heat, cool and transfer heat, photo 3. In a plate recuperator, the supply and exhaust air flows do not mix.
The plates are made of a material with high thermal conductivity, these include:
- special plastic;
- copper;
- aluminum.
Photo 3. Plate air recuperator
Advantages of a plate air recuperator :
- compact;
- relatively inexpensive;
- silent operation;
- high performance of the device (efficiency is 45...65%);
- no electric drive or dependence on electricity;
- long service life (practically do not break).
Disadvantage of the plate air recuperator:
- In winter, when there is frost, there is a high probability of freezing of the exhaust mechanism.
- No moisture exchange takes place.
- cylinder;
- rotating drum (rotor);
- frame.
Inside the cylinder there are many thin corrugated metal plates (heat exchangers).
Photo 4. Rotary recuperator
Using a rotating drum, the recuperator operates in two modes:
1 – passage of exhaust flow from the room;
2 – passing the supply air flow.
The operation of the rotary recuperator is controlled by its electronics, which, depending on the external and internal temperatures, determine the number of revolutions and operating mode. Thus, the metal plates either heat up or give off heat.
A rotary type recuperator may have one or two rotors.
Advantages of a rotary recuperator:
- High efficiency of the device. Efficiency reaches up to 87%.
- In winter, the device does not freeze.
- Does not dry out the air. Partially returns moisture back into the room.
Disadvantages of a rotary recuperator:
- Large dimensions of the equipment.
- Dependence on electricity.
Application area:
- Private houses;
- Office rooms.
- Garages.
Water recuperator
Water recuperator (recirculation) – this is a recuperator in which the heat exchanger is water or antifreeze, photo 5. This recuperator is similar in design to a traditional heating system. The heat exchanger fluid is heated by the exhaust air, and the supply air is heated by the heat exchanger.
Photo 5. Water recuperator
Advantages of a water recuperator:
- The normal indicator of operating efficiency, efficiency, is 50...65%.
- Possibility of installing its individual parts in different places.
Disadvantages of a water recuperator:
- Complex design.
- Moisture exchange is not possible.
- Dependence on electricity.
is a recuperator for industrial use. The efficiency of this type of recuperator is 55…68%.
This equipment is not used for private houses and apartments.
Photo 6. Roof air recuperator
Main advantages:
- Low cost.
- Trouble-free operation.
- Easy to install.
Self-made recuperator
If you have a desire, you can make an air recuperator yourself. To do this, you can carefully study the diagrams of recuperators that are available on the Internet and decide on the main dimensions of the device.
Let's look at the sequence of work:
- Selection of materials for the recuperator.
- Manufacturing of individual elements.
- Manufacturing of a heat exchanger.
- Assembly of the body and its insulation.
The easiest way to make a plate-type recuperator.
The following materials can be used to make the case:
- sheet metal (steel);
- plastic;
- tree.
To insulate the body, you can use the following materials:
- fiberglass;
- mineral wool;
- Styrofoam.
Konev Alexander Anatolievich
Ecology of consumption. Estate: Heat loss is a serious problem that construction science is struggling with. Effective insulation, sealed windows and doors only partially solve this problem. Heat leakage through walls, windows, roofs and floors can be significantly reduced. Despite this, energy still has one more wide path to “escape.” This is ventilation, which is impossible to do without in any building.
Heat loss is a serious problem that construction science is struggling with. Effective insulation, sealed windows and doors only partially solve this problem. Heat leakage through walls, windows, roofs and floors can be significantly reduced. Despite this, energy still has one more wide path to “escape.” This is ventilation, which is impossible to do without in any building.
It turns out that in winter we spend precious fuel on heating rooms and at the same time continuously throw heat out into the street, letting in cold air.
The problem of energy saving can be solved using a heat recuperator. In this device, warm indoor air heats outdoor air. This achieves considerable savings on heating costs (up to 25% of the total cost).
In the summer, when it is hot outside and the air conditioner is running in the house, the recuperator also brings benefits. It cools the hot incoming stream, reducing air conditioning costs.
Let's take a closer look at household heat recovery units to have an idea of their structure, advantages and features of choice.
Types, principle of operation and design of recuperators
The idea of using the heat from indoor air to heat outdoor air turned out to be very fruitful. It was the basis for the operation of all recuperators.
Today, three types of such devices are used:
- lamellar;
- rotary;
- recirculating water.
The most common and simplest in design are plate recuperators. They are non-volatile, compact, reliable in operation and have a fairly high efficiency (40-65%).
The main working part of such a device is a cassette, inside of which parallel plates are installed. The air leaving and entering the room is cut by them into narrow streams, each of which goes along its own channel. Heat exchange occurs through the plates. Street air is heated, and indoor air cools and is released into the atmosphere.
Operating principle of a plate recuperator
The main disadvantage of plate installations is freezing in severe frosts. Condensate settling in the recovery unit turns into ice and sharply reduces the performance of the device. Three ways have been found to combat this phenomenon.
The first is installing a bypass valve. Having received a signal from the sensor, it allows a cold flow to bypass the block. Only warm air passes through the plates, defrosting the ice. After defrosting and draining the condensate, the valve restores normal operation of the system.
The second option is to use plates made of hygroscopic cellulose. Water settling on the walls of the cassette is absorbed into them and penetrates into the channels through which the supply air moves. This solves two problems at once: eliminating condensation and humidification.
The third method is to preheat the cold stream to a temperature that prevents the water from freezing. To do this, a heating element is installed in the supply ventilation duct. The need for it arises when the outside air temperature is below -10C.
In recent years, plate reversible units have appeared on the market. Unlike direct-flow devices, they operate in two steps: the first is the release of warm air into the street, the second is the suction of cold air through a heated block.
Operating principle of reversible installation
Another type of installation is rotary recuperators. The efficiency of such devices is significantly higher than that of plate devices (74-87%).
The operating principle of the rotary unit is to rotate a cassette with cells in the flow of incoming and outgoing air. Moving in a circle, the channels alternately pass warm internal and cold external flows. In this case, the moisture does not freeze, but saturates the supply air.
It should be noted that the supply and exhaust unit with a rotary type recuperator allows you to smoothly regulate the heat transfer. This is done by changing the rotation speed of the cassette. The main disadvantage of rotary systems is the high cost of maintenance. In terms of reliability, they are also inferior to plate ones.
The next type is a recirculating water installation. It is the most complex in design. Heat transfer here is not carried out through the plates or rotor, but with the help of antifreeze or water.
The first liquid-air heat exchanger is installed on the exhaust duct, and the second on the suction duct. The work is carried out according to the principle of a heater: indoor air heats water, and it heats outdoor air.
The efficiency of such a system does not exceed that of plate recuperators (50-65%). The high price that one has to pay for the complexity of the design is justified by the only advantage: the units of such an installation can be placed not in one building, but in supply and exhaust ventilation areas remote from each other. For powerful industrial systems this is of great importance. Such devices are not installed in small buildings.
Features of choosing a recuperator
Having become familiar with the operating features of recuperation units, it’s time to move on to the practical part – the selection criteria for performing specific tasks.
The first thing you need to pay attention to is the installation method. Domestic supply and exhaust ventilation with heat recovery can be installed in its working position in several ways:
- Inside the wall. The housing is mounted in a pre-drilled hole. A cap is placed on the outside, and a grille and control unit on the inside.
- Indoors. The installation is hung on the wall. A grille or cap is placed outside.
- Outdoor placement. The advantages of this solution are obvious: minimal noise and space saving. The duct design of the device allows it to be placed on balconies and loggias, as well as simply on the facade of a building.
Another parameter that needs to be taken into account when purchasing is the number of fans. Budget air recuperators for the home are equipped with one ventilation unit that operates for both supply and exhaust.
More expensive devices have 2 fans. One of them pumps in and the other exhausts air. The performance of such devices is higher than that of single-fan devices.
When purchasing, you should also pay attention to the presence of an electric heater. With its help, freezing of the cassette is prevented and the lower temperature limit of the device’s operation is increased.
Climate control function. Allows you to accurately set the temperature to which the recuperator will heat the air.
Possibility of humidity control. This parameter significantly affects the comfort of the microclimate. A standard recuperator dries the air, removing moisture from it.
Presence or absence of a filter. An additional option that has a positive effect on the sanitary characteristics of the air mixture.
An important parameter that requires attention is the temperature of the pumped air. In different models, its value may differ significantly. The widest possible range of operating temperatures from -40 to +50C is rare for household devices.
Therefore, in addition to taking into account the optimal performance in m3/hour, when purchasing, choose a device that can fully operate in your climatic conditions.
Performance calculation
Detailed calculations of the operation of recuperators in the supply and exhaust ventilation system are quite complex. Here we have to take into account many factors: the frequency of air exchange in the premises, the cross-section of the channels, the speed of air movement, the need to install mufflers, etc. Only experienced engineers can competently perform such a task.
The average consumer can use a simplified method to correctly navigate when purchasing a device.
The performance of the recuperator directly depends on the sanitary standard of air flow per person. Its average value is 30 m3/hour. Therefore, if 4 people permanently live in an apartment or private house, then the installation productivity should be at least 4x30 = 120 m3/hour.
The own electrical power of household recuperators is small (25-80 W). It is determined by the level of energy consumption of duct fans. In installations with electric heating of the incoming flow, heating elements with a total power of 0.8 to 2.0 kW are installed.
Popular brands and approximate prices
When choosing a household recuperator, you should focus on manufacturers and models that have earned high customer ratings. As an example, we can cite the products of foreign companies Electrolux (Electrolux), Mitsubishi (Mitsubishi), Marley (Marley).
Recuperator for small premises Mitsubishi Electric VL-100EU5-E. Air consumption 105 m3/h. Price from 21,000 rub.
Popular model from Electrolux. Estimated retail price from 42,000 rubles.
The 2017 price tags for household installations of these brands start at 22,000 rubles and end at 60,000 rubles.
MARLEY MENV-180. Air consumption 90 m3/hour. Cost from 27,500 rub.
The equipment of Russian and Ukrainian companies Vents (Vents), Vakio (Vakio), Prana and Zilant has proven itself well. Not inferior to foreign analogues in performance and reliability, they are often more affordable.
Installation of Vakio. Capacity 60 m3/h in recovery mode, up to 120 m3/h in supply ventilation mode. Price from 17,000 rub.
The estimated cost of air recovery systems from these companies (capacity from 120 to 250 m3/hour) ranges from 17,000 to 55,000 rubles.
Prava 200G. Inflow - 135 m3/h, exhaust - 125 m3/h. The recommended area for servicing the system is up to 60 m2.
The nature of reviews about air recuperators is mostly positive. Many owners note that with their help, the problem of excess humidity, which caused the appearance of mold and mildew in the premises, was solved.
In calculations of the payback period for this equipment, figures from 3 to 7 years are given. We did not find any data from instrumental measurements regarding real energy savings on forums dedicated to this topic.
Briefly about self-assembly
Most photo and video instructions for making recuperators yourself discuss plate models. This is the simplest and most affordable option for the home craftsman.
The main part of the structure is the heat exchanger. It is made from galvanized steel, cut into plates measuring 30x30 cm. To create channels at the edges and in the middle of each section, plastic strips 4 mm thick and 2-3 cm wide are glued with silicone.
The heat exchanger is assembled by placing and alternately rotating the plates at an angle of 90 degrees relative to each other. This creates isolated channels for the oncoming movement of cold and warm air.
After this, a housing made of metal, chipboard or plastic is made to fit the dimensions of the heat exchanger. There are four holes in it for air supply. Two of them have fans. The heat exchanger is rotated at an angle of 45 degrees and secured in the housing.
The work is completed by thoroughly sealing all installation joints with silicone.
Heat recovery has become quite often used recently in ventilation systems. If we consider the process itself in more detail, we must first decide and understand what the term recovery itself means. Heat recovery in ventilation systems means that the air being passed through, which is removed by special installations, is passed through a filter system and supplied back.
It is worth paying special attention to the fact that in ventilation systems, with a share of exhaust air, part of the heat is also drawn out of the room. And it is this thermal energy that returns back.
These systems are effectively used in large industries and large workshops, since in order to ensure the optimal temperature for such premises in winter it is necessary to incur large expenses. These installations can significantly compensate for such losses and reduce costs.
Even in a private home, ventilation units with heat recovery will be quite relevant today. Even in an individual house, ventilation is always carried out and when air circulates, heat also leaves any room. Agree that it is simply impossible to seal the building completely and thereby avoid any heat loss.
Today, these systems should be used even in a private home for the following reasons:
- For quick removal of air with a large admixture of carbon dioxide;
- To bring in the required amount of fresh air into living spaces;
- To eliminate high humidity in rooms, as well as eliminate unpleasant odors;
- To save heat;
- And also to remove dust and harmful microorganisms that may be contained in it.
Supply air systems with recovery
An air handling unit with heat recovery is beginning to be in increasing demand among private homeowners. And its advantages, especially in the cold season, are very high.
As you know, there are many ways to provide a living space with the necessary ventilation. This is also natural air circulation, which is mainly carried out by ventilating rooms. But you must admit that it is simply impossible to use this method in winter, since all the heat will quickly leave the living quarters.
If in a house in which air circulation is carried out only naturally there is no more efficient system, then it turns out that in the cold the rooms do not receive the required volume of fresh air and oxygen, which subsequently negatively affects the well-being of all family members.
Of course, recently, when almost all owners are installing plastic windows and doors, it turns out that arranging ventilation in a natural way is simply ineffective. Therefore, there is a need to install additional equipment that can ensure good air circulation indoors. And, of course, every owner will agree that they would like any system to use energy sparingly.
And here the best option would be heat recovery in ventilation systems. Ideally, it is advisable to purchase a unit that could also provide humidity recovery.
What is moisture recovery?
Any room should always maintain a certain level of humidity at which each person feels most comfortable. This norm ranges from 45 to 65%. In winter, most people experience excessively dry indoor air. Especially in apartments, when the heating is turned on full and the air becomes very dry with a humidity of about 25%.
In addition, it often turns out that not only humans suffer from such changes in humidity. But also floors with furniture, as we know, wood has high hygroscopicity. Very often, furniture and floors dry out from too dry air, and in the future it turns out that the floors begin to creak and the furniture begins to fall apart. These installations will primarily maintain the required level of humidity in any room, regardless of the time of year.
Types of recuperators
In individual residential buildings, ventilation systems with centralized heat exchangers are most often installed. In addition, today you can choose from several types of recuperative ventilation designs, but the following are in higher demand:
- Lamellar.
- Rotary.
- Chamber.
- Having an intermediate coolant.
Plate type heat exchangers
The simplest designs for ventilation systems. The heat exchanger is made in the form of a chamber divided into separate channels located parallel to each other. Between them there is a thin plate partition, which has high thermal conductivity properties.
The principle of operation is based on the exchange of heat from air flows, that is, exhaust air, which is removed from the room and gives up its heat to the supply air, which enters the house already warm, thanks to this exchange.
The advantages of this technology include:
- easy device setup;
- complete absence of any moving parts;
- high efficiency.
Well, one of the most significant drawbacks in the operation of such a recuperator is the formation of condensation on the plate itself. Typically, such heat exchangers require additional installation of special drop eliminators. This is a necessary parameter, since in winter the condensate can freeze and stop the device. That is why some devices of this type have built-in defrosting systems.
Rotary heat exchangers
Here the main part is taken over by the rotor, which is located between the air ducts and heats the air through constant rotation. Ventilation with heat recovery rotor type has very high operating efficiency. This system allows you to return about 80% of the heat back into the room.
But a significant drawback is the inferior performance of the system regarding dirt, dust and odors. There are no densities in the design between the rotor and the housing. Because of them, air flows can mix and therefore all contaminants can come back again. And naturally, the noise level here is an order of magnitude higher than that of a plate heat exchanger.
Chamber type heat exchangers
In this type of recuperator, the air flows are separated directly by the chamber itself. Heat exchange occurs thanks to a damper that periodically changes the direction of air flow. This system is highly efficient in operation. The only disadvantage is the presence of moving parts inside the device.
Heat exchangers with intermediate media
The operating principle of this device is almost similar to the operation of a plate recuperator. Here the heat exchanger is a closed loop of a tube. There is a constant circulation of water or a water-glycol solution in it. The efficiency of heat exchange processes directly depends on the circulation rate in a closed fluid circuit.
In such a device, mixing of air flows is completely eliminated. The only downside is the lack of efficiency. Such a device is capable of returning approximately 50% of the heat taken from the room.
Heat pipes
It is worth highlighting one more type of recuperator. Heat recovery in a home using heat pipes is quite effective. Such devices are sealed tubes made of metal that has high heat-conducting properties. Inside such a tube there is a liquid that has a very low boiling point (freon is usually used here).
Such a heat exchanger is always installed in a vertical position, with one of its ends located in the exhaust duct and the other in the supply duct.
The principle of operation is simple. The drawn out warm air, washing the pipe, transfers heat to the freon, which, boiling, moves upward with a large amount of heat. And the supply air washing the top of the tube takes this heat with it.
The advantages include high efficiency, quiet operation and high efficiency. So today you can save a lot on heating your home, paying some of it back.