Comparison Cooper&Hunter CH-HRV3.5KDC vs Cooper&Hunter CH-HRV3K2

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.

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.

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.

Electrical power consumed by the air handling unit in normal operation (for models with capacity control - at maximum speed). Knowing this power, you can determine the requirements for connecting the unit, as well as estimate how expensive its operation will be in light of electricity bills. It should be taken into account that for models with an electric reheater (see “Type of reheater”), in this case we are talking about the power of only the ventilation system, and the power of the reheater is given separately (see above); thus, the total power consumption when operating in full format will correspond to the sum of these powers.

Also, based on the power consumption, you can to a certain extent evaluate the performance of the installation: “gluttonous” units usually provide an appropriate flow.

The country claimed as the "homeland" of the unit. There are many stereotypes associated with the "nationality" of products, but most of them are not justified. Firstly, the country of origin of the goods is most often indicated by the country of origin of the brand, and the latter may not coincide with the place of actual production. However, this cannot be called a deception: a conscientious manufacturer monitors the quality of their products, wherever they are produced. Secondly, the origin from a highly developed country is not yet a guarantee of quality, and in less "popular" countries, thanks to the development of technology, high-quality equipment may well be produced. Therefore, it is more worth evaluating the level of a product by the reputation of the brand, rather than the country, and it makes sense to pay attention to the origin if you fundamentally intend to support (or do not want to support) a company from a certain state.

Now the following countries of origin are represented on the market: Germany, Denmark, Italy, Lithuania, China, the Netherlands, Sweden, Czech Republic, Japan.