Comparison VENTS Micra 150 E vs VENTS Micra 60

Additional functions provided in the design of the unit in addition to ventilation.

— Recuperator. A heat exchanger that prevents "blowing" heat from the room during the cold season. The principle of operation of the heat exchanger is that it takes energy from the blown air and transfers it to the incoming one — thus, ventilation sends relatively cool air out and supplies preheated air into the room. The use of a heat exchanger can significantly reduce heat loss and, accordingly, heating costs — the amount of heat returned in the most advanced heat exchangers can reach 97% (see "Heat exchanger efficiency"). At the same time, such systems are often passive and do not themselves consume energy (and where it is required, the consumption is still lower than the amount of saved heat). Naturally, this function is found only in full-size, supply and exhaust units (see "Type of ventilation"). Note that external recuperators are also produced, which can be supplemented with ventilation units that do not have this function; however, an integrated heat exchanger is often more convenient and efficient.

— Heater. The built-in heater intended for heating the air coming into the room. At the same time, in contrast to the heat exchanger described above, energy is used...for heating from a third-party source — an electric heater or a water heat exchanger (see "Heater type"). This method of heating requires additional energy costs, and water circuits are also quite troublesome to connect. But it is much more efficient: if the air supplied from the heat exchanger into the room cannot be warmer than the air blown out, then this is not a problem for the heater. This function is mainly used to raise the temperature of the supply air supplied from the heat exchanger (built-in or separate) to the temperature of the extract air and thus avoid unnecessary heat losses.

— Cooler. A built-in system that reduces the temperature of the air supplied to the room. Simplified, this function can be called a "built-in air conditioner" — because air conditioners are usually used to cool the air in hot weather. In fact, in some cases, installing an air ventilation unit with a cooler can eliminate the need for separate air conditioners. On the other hand, such systems are quite complex and expensive, and therefore they are used rarely, mainly among centralized units(see "System").

— Humidifier. A system that increases the humidity of the air supplied to the room. The peculiarity of the human body is such that the feeling of a comfortable climate depends not on the absolute, but on the relative humidity of the surrounding air. Relative humidity, on the other hand, depends not only on the actual amount of water vapour in the air but also on temperature: physical laws are such that as the temperature rises, relative humidity drops, even though the amount of moisture in the air remains unchanged. In fact, this leads to the fact that during the cold season, the heated outside air begins to seem dry. To avoid this effect in climate technology, including air ventilation units, humidification systems may be provided. Note that such systems usually require either a connection to the water supply system or regular refilling of the water tank.

— Ionizer. A system that saturates the air entering the room with negatively charged ions. The effect of such ions on the climate is positive — the air feels fresher, ionization contributes to the sedimentation of contaminants on the floor and walls and provides a bactericidal effect. In addition, it is believed that ionized air is good for health, improves immunity and recovers from injuries and illnesses.

The lowest performance with which the supply-exhaust unit can operate.

For performance in general, see "Maximum air flow". Here we note that it makes sense to indicate the minimum flow only in cases where the amount of air passed can be regulated (see "Number of fan speeds"). And even then, for such models, this parameter is not always given.

The highest performance of the air ventilation unit; or, if the air flow control is not provided for in the design, the nominal capacity of the unit.

In this case, air flow refers to the amount of air that the unit can pass through itself per hour. The optimal air flow value for each room is calculated by the formula "room volume multiplied by the air exchange rate"; the air flow must not be lower than this indicator; otherwise, we cannot talk about effective ventilation. The volume is easy to calculate by multiplying the area of the room by the height of the ceilings, and the multiplicity indicates how many times per hour the air in the ventilated space should be updated. It depends on the type and purpose of the room: for example, a multiplicity of 1 is enough for a residential apartment, and at least 4 is required for a pool (there are special tables by which you can determine the multiplicity for each type of room). Thus, for example, for an apartment with a living area of 70 m², a ceiling height of 2.5 m and a kitchen of 9 m² (air exchange rate of at least 2), a duct of at least 70*2.5*1+9*2.5*2=220 m³ (excluding bathroom and toilet, they have their requirements for multiplicity).

It should be noted that a certain flow margin (about 10–15%) will not be superfluous, but it hardly makes sense to chase higher rates — after all, performance requires appropriate power, which, in turn, affects the dimensions, price and...energy consumption of the installation.

The noise level produced by the air ventilation unit in normal operation.

This parameter is indicated in decibels, while the decibel is a non-linear unit: for example, a 10 dB increase gives a 100 times increase in sound pressure level. Therefore, it is best to evaluate the actual noise level using special tables.

The quietest modern ventilation units produce about 27–30 dB — this is comparable to the ticking of a wall clock and allows you to use such equipment without restrictions even in residential premises (this noise does not exceed the relevant sanitary standards). 40dB is the daytime noise limit for residential areas, comparable to average speech volume. 55–60 dB — the norm for offices, corresponds to the level of loud speech or sound background on a secondary city street without heavy traffic. And in the loudest, they give out 75–80 dB, which is comparable to a loud scream or the noise of a truck engine. There are also more detailed comparison tables.

When choosing according to the noise level, it should be taken into account that the noise from the air movement through the ducts can be added to the noise of the ventilation unit itself. This is especially true for centralized systems (see "System"), where the length of the ducts can be significant.

The heat transfer efficiency, energy saving indicators and service life of the unit directly depend on the material of the heat exchanger. Most often, heat exchangers of supply and exhaust units are made of the following materials:

- Aluminum. Aluminum is a lightweight metal with good thermal conductivity for efficient heat transfer between air streams. Aluminum heat exchangers quickly respond to temperature changes due to rapid heating and cooling, but just as quickly condense in a humid environment. In addition, aluminum dust particles, when released into the air, pose a potential threat to the human respiratory system.

— Cellulose. Heat exchangers made of cellulose are lightweight and extremely inexpensive to manufacture. However, in terms of thermal conductivity and wear resistance, cellulose is an ineffective material and is therefore quite rare. On a separate line, it is important to mention that cellulose tends to absorb unpleasant odors, and its cleaning process does not involve washing or other contact with water.

— Ceramics. Ceramics as a material for the manufacture of heat exchangers is valued for its wear resistance and high safety, but the cost of such models is often very high. In terms of heat transfer efficiency, ceramics can be called the “golden mean” - it is capable of quickly accumulating heat, but also retains it well, witho...ut completely releasing it to the supply air. This advantage turns into a disadvantage when recovering cold air during the heating period.

- Copper. Heat exchangers made of copper are characterized by high thermal conductivity - copper accumulates and releases heat best, but also cools down just as quickly. The downside of large temperature changes is the formation of condensation, which at low temperatures leads to freezing and a complete stop of ventilation. To avoid freezing, additional heating is used, and this often leads to increased power consumption. However, copper heat exchangers provide the highest efficiency (over 90%), prevent the formation of viral, fungal and bacteriological air pollutants due to natural antiseptic properties, and withstand many years of use. In terms of their combination of qualities, copper heat exchangers are among the best in their class.

— Polystyrene. Some air handling units may use heat exchangers with plates made of plastic, polystyrene and other polymer-based materials. They are lightweight and corrosion resistant, but often have lower thermal conductivity. Another flaw in such materials is that many viruses and bacteria can remain viable for quite a long time on the plastic surfaces of the heat exchanger.

Efficiency of the heat exchanger used in the heat exchanger of the supply and exhaust system (see "Features").

Efficiency is defined as the ratio of useful work to the energy expended. In this case, this parameter indicates how much heat taken from the exhaust air, the heat exchanger transfers to the supply air. The efficiency is calculated by the ratio between the temperature differences: you need to determine the difference between the outdoor air and the supply air after the heat exchanger, the difference between the outdoor and exhaust air, and divide the first number by the second. For example, if at an outside temperature of 0 °С, the temperature in the room is 25 °С, and the heat exchanger produces air with a temperature of 20 °С, then the efficiency of the heat exchanger will be (25 – 0)/(20 – 0)= 25/20 = 80%. Accordingly, knowing the efficiency, it is possible to estimate the temperature at the outlet of the heat exchanger: the temperature difference between the inside and outside must be multiplied by the efficiency and then the resulting number is added to the outside temperature. For example, for the same 80% at an outdoor temperature of -10 °C and an internal temperature of 20 °C, the inflow temperature after the heat exchanger will be (20 – -10)*0.8 + -10 = 30*0.8– 10 = 24 – 10 = 14 °C.

The higher the efficiency, the more heat will be returned to the room and the more savings on heating will be. At the same time, a highly efficient heat e...xchanger is usually expensive. Also note that the efficiency may vary slightly for certain values of the external and internal temperatures, while manufacturers tend to indicate the maximum value of this parameter — accordingly, in fact, it may turn out to be lower than the claimed one.

— Electric heater. Heaters are called devices designed to increase the temperature of the air entering the room; such devices are installed behind the heat exchanger (when viewed from the outside). And the electric principle of heating is the most popular among the heaters. It is due to the simplicity and ease of installation: all the necessary equipment is already in the ventilation unit, you just need to supply power. The disadvantage of this option is considered to be a rather high power consumption; in addition, most powerful electric heaters require a 400 V power supply, and such a connection is far from being available everywhere — additional wiring may be required.

— Water heater. Heater powered by a water heat exchanger. See above for more details on heaters in general; the heat exchanger is connected to a heating system powered by a boiler or other heater. The main advantage of this option is the fact that the heater itself does not consume electricity and is often cheaper to operate (especially if the boiler runs on gas or solid fuel), even though its power can be very impressive. In addition, by directing part of the heating power to heating the air, it is possible to achieve a more efficient use of the boiler capacity. At the same time, connecting a water heater is a rather complicated matter, which is why such devices are used somewhat less often than electric ones.
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— Water and electric heater. The presence in the design of both water and electric heaters. See above for details of each variety; their combination in one unit increases the overall efficiency, allows you to adjust the heating power and choose the type of heater depending on the situation. For example, in winter, you can mainly use a water heater, including an electric one only when the outside air temperature drops sharply when the water heat exchanger is no longer enough. And in case of an unexpected cold snap in the warm season, when there is no need to start the boiler, you can turn on only the electric heater and provide heat in the room. On the other hand, such versatility significantly affects the price, but in fact, it is rarely required. Therefore, this option has not received much distribution.

— Electric preheater. Electric pre-heater installed outside of the heat exchanger — in such a way that the outside air first enters the pre-heater, then the heat exchanger (unlike heaters, which heat the air after the heat exchanger). In addition to the actual heating, such a device is also designed to protect the heat exchanger from freezing during the cold season (or to defrost an already frozen heat exchanger).

— Electric heater and preheater. A design that combines two types of electric heaters at once — a heater and a preheater. About the features of both, see below, but here we note that such a combination provides high heating efficiency. However, it is not cheap.

The power of the main heater used in the air ventilation unit. For models with two heaters (see "heater type"), this item indicates the power of the main heating element; at the same time, in units with water-electric heating, the water heat exchanger is considered the main one, in units with a preheater and afterheater, the afterheater.

Power determines primarily the amount of heat produced by the heater. This parameter is selected by the designers for the performance of the installation so that the power is enough for the volume of air passing through the unit. Thus power is more of a reference parameter than practically significant: most likely, it will be enough one way or another for the effective use of the installation. We note only some of the nuances associated with particular types of heaters. So, in water heaters, the actual power depends on the temperature of the supplied coolant; in the characteristics, indicators are usually given for a temperature of 95 °C, at a lower value and power, respectively, will be lower. With electric heating, the power consumption of the heater and, accordingly, the requirements for its connection directly depend on the power.

The lowest outdoor air temperature at which the ventilation unit can be safely used; more precisely, the minimum inlet air temperature at which the unit can operate normally, without malfunctions, for an indefinitely long time.

It is worth choosing according to this parameter taking into account the climate in which it is planned to use the unit: the device should normally tolerate at least the average winter temperature, and it is best to have some reserve in case of a harsh winter. However, many modern models allow operation at -10 °C and below, and in the most cold-resistant ones, the temperature minimum can reach -35 °C. So choosing a unit for a temperate climate is usually not a problem. Also note that if an installation that is ideally suited for all other parameters cannot cope with low temperatures, the situation can be corrected by using an additional heater at the inlet of the ventilation system.

Note that if the minimum temperature is not indicated in the characteristics, it is best to proceed from the fact that this model requires a temperature not lower than 0 °C. In other words, in cold weather, it is worth using only the equipment for which this possibility is directly stated.