Nominal capacity BTU
The British Thermal Unit (BTU) is used to indicate the rated capacity of air conditioners in cooling mode. The parameter is indicated mainly for split and multi split systems with wall installation. Capacity is indicated in BTU per hour, while 1 BTU/h is equal to about 0.293 watts. The rated capacity of an air conditioner is often a multiple of 1000 BTU. The indicator determines how many thousand BTU/h the air conditioning equipment provides. For example, the marking "9 BTU" here means a unit for 9000 BTU/h or about 2600 watts of effective capacity.
The practical meaning
of the capacity is that by BTU you can easily determine the recommended area of a standard room in square meters: just multiply the figure indicated in the characteristics by 3. So, for 9 BTU it will correspond to 9*3=27 m². Note that there is no strict relationship between BTU and watts in this list: for example, air conditioners with an effective capacity of 2360 to 2900 W fall into the same category of 9 BTU. In practice, even such an approximate ratio is enough to understand which air conditioner should be considered for cooling certain area.
Air flow
The amount of air that an air conditioner can pass through itself in an hour.
This parameter depends on the power and the overall level of the device, but there is no strict dependence here: models with the same effective capacity may differ in air circulation speed. In such cases, it is worth proceeding from the fact that a higher speed contributes to uniform cooling/heating of the air and reduces the time required to create a given microclimate; on the other hand, higher-performing air conditioners use more energy, are larger and/or cost more.
Min. T for cooling mode
The lowest outdoor air temperature at which the air conditioner can operate normally in cooling mode.
The need for air cooling arises not only in hot weather — for example, efficient heat dissipation is constantly needed in closed rooms with a lot of heat-generating equipment (such as server rooms). And the limitation on the minimum outdoor temperature is because a large temperature difference between the condenser (heater) of the outdoor unit and the environment can damage the circuits.
Note that in domestic air conditioners, this limit can be quite high — +20 °С and even higher (up to +25 °С); however, additional cooling is usually required for warmer weather, and such air temperatures are not so high as to cause significant discomfort. But in professional units, the minimum temperature for the cooling mode can be significantly below zero — up to -40 °C and even lower.
It is also worth mentioning that in the presence of a heating mode, the permissible temperature for it is noticeably lower than for the cooling mode. It is due to the difference between the formats of the air conditioner in these modes.
Min. T for heating mode
The lowest outdoor temperature at which the air conditioner can operate normally in heating mode.
Modern air conditioners with heating mode are quite cold-resistant appliances. Thus, models where this temperature limit exceeds 0 °C are rare. A lot of units, even quite inexpensive ones, have a minimum temperature allowed for heating in the range of
-5 ... -10 °C or
-11 ... -15 °C. Models with indicators of
-16 ... -20 °C and
-21 ... -25 °C, although much less, are still quite a few, and air conditioners capable of heating at
-25 °C and below are very close in terms of capabilities to heat pumps.
Maximum pipe length
The maximum allowable length of the refrigerant pipes connecting the outdoor and indoor unit of a split or multi split system (see "Type"). The length of the tubes is implied in one direction, from the indoor unit to the outdoor unit (or vice versa).
In most modern air conditioners, this parameter is about 15 – 20 m or even more, so problems with the maximum length can only arise if the units are far from each other. It is technically possible to use tubes longer than the maximum allowed, but this will affect the efficiency of the air conditioner and may require refilling the freon.
Indoor unit dimensions (WxHxD)
Dimensions of the indoor unit of the air conditioner in height, width and depth.
These dimensions allow you to estimate how much space you need to place the device. In this case, of particular importance — mainly for split and multi split systems with wall mounting is the width of the indoor unit. The fact is that in terms of the height and depth of the internal blocks, most of these systems differ slightly in general but the differences in width are much more noticeable. So, the narrowest models have a width of
76 – 80 cm or
less, and the largest ones occupy
91 – 95 cm, and often
more. At the same time, the more powerful the air conditioner, the wider it is, usually, but there is no rigid dependence here.