Max. heat output
The maximum heat output generated by a heat pump is the amount of heat it can transfer from the outdoors into the heating system and/or domestic hot water.
The heat output is the most important spec of a heat pump. It directly determines its efficiency and ability to provide the required amount of heat. Note that this spec is shown for optimal operating conditions. Such conditions are rare, so the actual output heat is usually noticeably lower than the maximum; this must be taken into account when choosing. There are special formulas for calculating the optimal value of the maximum heat output, depending on the specific condition.
Heat output (~ 0 °C)
Heat output is the amount of heat generated by a heat pump at a source temperature (air or ground - see above) of about 0 °C. This indicator is more visual and closer to reality than the maximum heat output (see above), so it is often indicated in the characteristics as the main one.
The required heat output depends on the area and some features of the room, on the need for hot water and a number of other factors; for its calculation in special sources, you can find the appropriate formulas.
Max. cooling output
Maximum cooling output delivered by the pump.
The pump operates in the cooling mode removing excess heat from the room to the environment — it plays the role of an air conditioner. The required cooling capacity depends on the area of the building, the specs of its thermal insulation and some other factors; methods of its calculation can be found in special sources. Also note here that conventional heating equipment (radiators, underfloor heating) is not suitable for cooling, for this it is necessary to use special equipment (for example, fan coil units).
Max. water temperature
The highest temperature to which the pump can heat the coolant. It is worth noting that such indicators can be achieved at a fairly high temperature of air or ground. And since heat pumps are used during the cold season, the actual maximum temperature, usually, is less than theoretically achievable. Nevertheless, this parameter makes it possible to evaluate the capabilities of the unit or its suitability for certain tasks.
t°C outside
Outside temperature for which the COP is given. See below for details on this coefficient and the value of the outdoor temperature.
COP
The COP (coefficient of performance) is a key characteristic that describes the overall efficiency of a heat pump. It represents the ratio between the thermal power and power consumption of the unit (see above) – in other words, how many kilowatts of thermal energy the pump produces per 1 kW of electricity consumed. In modern heat pumps, this figure can exceed 5.
However, note that the actual COP value may vary depending on the outside temperature and the supply temperature. The higher the difference between these temperatures, the more resources are needed to “pump” thermal energy and the lower the COP will be. Therefore, in the specifications it is customary to indicate the COP value for specific temperatures (and in many models – two values, for different options) – this allows you to evaluate the actual capabilities of the unit.
Supply t°C
Temperature in the flow pipe for which an additional COP is specified. See below for more details on this coefficient. And this temperature is the temperature of the heat carrier at the outlet of the pump, at which the given COP value is reached.
Note that manufacturers often go to the trick and measure COP for a relatively low temperature (much lower than the maximum temperature of the heat carrier — for example, 35 °C for a model with a maximum of 55 °C). This allows them to give quite impressive performance figures in the specifications. However, at higher temperatures, the actual energy cost per unit of thermal power will be greater and the actual COP will be lower.
COP
Additional heat coefficient COP specified in the specifications in addition to the main one. For more information about the meaning of this indicator, see the "COP" above. And an additional coefficient is indicated for operating temperatures other than the main one — this allows you to evaluate the capabilities of the pump in different conditions.
Refrigerant
Type of refrigerant (freon) used in the heat pump.
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R22. An outdated type that was popular some time ago, but is rarely used today. Differing in several advantages (low cost, low operating pressure, uniformity), R22 is at the same time environmentally unsafe (harmful to the ozone layer). Therefore it is gradually falling into disuse, although it is still found in some inexpensive models.
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R134A. Tetrafluoroethane-based refrigerant is related to ozone-friendly freons (however, we cannot talk about complete environmental safety, because R134A has a high global warming potential GWP). It has a homogeneous composition, which allows you to refuel the system without problems in case of leaks. However, it has specific requirements for compressors and lubricants (polyester oils are required), which affects the cost.
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R407C. It is another replacement for R22. It is quite efficient and environmentally friendly, but it is expensive, and it has a high operating pressure (which accordingly affects the price of equipment). In addition, it is anisotropic — it is a mixture of several freons with different boiling points and, in case of a leak, it is necessary to completely change the entire volume of the refrigerant.
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R410A. Like R407C, this freon is ozone-safe, but it requires even higher operating pressur
...es (and, accordingly, reliable and expensive equipment), and it is not cheap. On the other hand, R410A components have the same boiling point, and in the event of a leak, it is not necessary to change the refrigerant completely — just replenish it.
— R32. A fairly advanced refrigerant that combines three key advantages: efficiency, environmental friendliness and isotropy. This substance does not destroy the ozone layer and does not have a significant impact on global warming; a homogeneous composition allows you to refuel the heat pump without problems in the event of a freon leak. The main disadvantage of models with this type of refrigerant is the high price associated not so much with the cost of the R32 itself but with the specific requirements for the design of the working circuit.
