Comparison Systemair SAVE VSR 300 vs Daikin VAM 250FC

The diameter of the holes intended for connecting air ducts to the ventilation unit. The more performant the air ventilation unit, the more air the ducts must pass and the larger, usually, the mounting holes. For wall-mounted models (see above), this parameter determines the size of the channel that must be drilled into the wall to accommodate the unit.

Class of air purification, which corresponds to the supply and exhaust unit.

This parameter characterizes how well the unit is able to clean the air supplied to the room from dust and other microparticles. Most often it is specified according to the EN 779 standard, and the most common classes in ventilation units are as follows:

— G3. Marking G denotes coarse filters designed for rooms with low requirements for air purity and retaining particles with a size of 10 microns or more. In residential ventilation systems, such devices can only be used as pre-filters; additional equipment will be required for additional purification. Class G3 is the second most efficient coarse cleaning class, it means a filter that removes from the air 80 – 90% of the so-called synthetic dust (test dust on which filters are tested).

— G4. The most effective class of coarse filters (see above), which involves the removal of at least 90% of particles of 10 microns or more in size from the air.

— F5. Classes with index F correspond to fine cleaning, the effectiveness of which is assessed by the ability to remove particles from the air with a size of 1 µm. Such filters can already be used for post-purification of air in residential premises, including even hospital wards (without increased cleanliness requirements). F5 is the lowest of these classes, suggesting an efficiency of removing such dust at the level of 40 – 60%.

— F6. Fine cleaning class (see above), removal from the air of 60 – 80% of particles with a size of 1 µm.

— F7. Fine cleaning class (see above), corresponding to the removal of 80 – 90% of dust from the air with a size of 1 µm.

— F8. Fine cleaning class (see above), providing the removal of 90 to 95% of dust from the air with a size of 1 µm and above.

— F9. The most efficient class of fine cleaning; the higher efficiency corresponds to the ultra-fine cleaning class H (see below). Class F9 achieves dust removal efficiency of 1 µm at 95% and above.

– H10 – H13. Classes H are used to mark filters of ultra-fine (absolute) purification (HEPA filters) capable of removing particles of the order of 0.1 - 0.3 microns in size from the air. Such filters are used in rooms with special requirements for air purity – laboratories, operating rooms, high-precision industries, etc. In filters corresponding to the H10 class, the efficiency of cleaning from the mentioned particles is 85%. H11 claims 95% absorption. And class H12 and H13 are the most efficient with particle retention of at least 99.95% and 99.99% respectively.

— Carbon filters. Created on the basis of activated carbon or other similar adsorbent. Effectively trap volatile molecules of various substances, thanks to which they perfectly eliminate odors. Carbon filters are subject to mandatory replacement after the resource is exhausted, since if the service life is exceeded, they themselves can become a source of harmful substances.

The number of speeds at which the fans of the air ventilation unit can operate.

The presence of several speeds allows you to choose the actual performance of the installation, adjusting it to the specifics of the current situation: for example, in a production room, you can reduce the ventilation intensity during the night shift, where there are fewer people than in the daytime. And the more speeds provided in the device (with the same performance range) — the more choice the user has, the easier it is to find the mode that best suits current needs.

Note that if the minimum and maximum of the air flow are indicated in the specs, but the number of speeds is not given, this does not necessarily mean smooth adjustment. On the contrary, most often such models are regulated traditionally, in steps, but for some reason, the manufacturer decided not to specify the number of speeds in the characteristics.

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.

Static pressure created by the air handling unit at the inlet.

This parameter is required for calculations related to the selection of the installation for a ventilation system with long air ducts. The static pressure must be equal to the resistance of the duct network at a given air flow. More detailed information about this parameter and its application can be found in special sources.

The type of heat exchanger used in the heat exchanger of the ventilation unit (see "Features").

— Plate. The simplest and most common type of heat exchanger is based on the use of metal plates that separate the incoming and outgoing air into narrow channels. Such heat exchangers are inexpensive, do not require an electrical connection and are almost silent. However, a classic plastic or metal heat exchanger has a relatively low efficiency (about 45 – 80%), “blows out” moisture from the room (which may require the use of humidifiers), and in frosty weather ice forms on the plates, and it is necessary to turn off the heat exchanger, letting air in bypassing it (for this, an automatic bypass is often provided). The last two shortcomings are devoid of plate heat exchangers made of cellulose — they do not freeze; moreover, they retain not only heat but moisture in the room, and the efficiency can reach 92%. On the other hand, cellulose heat exchangers are not applicable in swimming pools and other areas with high humidity.

— Rotary. Heat exchangers, the operation of which is based on the rotation of a disc of a special design. At the same time, each part of the heat exchanger alternately works to cool the exhaust air and then to heat the supply air. Such a system has a higher efficiency than plate heat exchangers, it is more compact, it returns most of the moisture coming out with the...exhaust air and does not freeze in cold weather. On the other hand, due to the complexity of the design, rotary heat exchangers are more expensive and less reliable, in addition, they require power supply and produce some additional noise (although most often not much).

— Enthalpy. The key feature of enthalpy (ceramic) heat exchangers is that they transfer to the supply air not only sensible, but also latent heat of the exhaust air, which is released due to moisture condensation. In addition, the design of such heat exchangers provides for the presence of a special membrane made of cellulose or synthetic fabric - it is this that is responsible for transferring heat and moisture to the supply air, thereby ensuring the maintenance of optimal microclimate parameters. This allows you to achieve impressive efficiency indicators - from 90% and above. The main disadvantage of enthalpy heat exchangers is their high cost due to the complexity of production.

— Tubular. Heat exchanger based on a bundle of thin metal tubes of great length placed in a casing. Usually, outdoor air is supplied through such tubes to the room, and the air from the room on the way out moves between the tubes, transferring heat to them. In such devices, you can achieve a fairly solid efficiency — 70% and above; even though tubular heat exchangers are relatively simple in design and reliable. They appeared relatively recently and, for the most part, have not yet received significant distribution.

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.

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.

The presence of a remote control in the delivery set of the air ventilation unit.

This configuration is provided in most decentralized models (see "System"). However, it is often found in centralized ones. The possibility of a remote control provides additional convenience for the user — you do not need to approach the unit every time. In addition, many control functions can be transferred to the remote control, making the installation itself more compact (this is true for the mentioned decentralized equipment, which has a rather small size).

Note that the remote control can be both portable and wall-mounted, designed to be permanently in one place (like a wall light switch).