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.
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).
Power consumption (heating)
Electric power consumed by the heat pump when operating only for heat transfer, without the use of an additional heating element (if any, see below). The ratio of thermal power to power input determines the thermal coefficient COP (see below) and, accordingly, the overall efficiency of the unit. It also affects overall power consumption (and therefore electricity bills), as well as some power and connection requirements — for example, models powered by 230 V and with a power of more than 5 kW cannot work from an outlet and require a special connection to the mains.
Power consumption (cooling)
For more information on power consumption, see the paragraph above. Here is indicated the consumption of electricity during operation in the cooling.
Power source
Type of power supply used by the heat pump.
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Single-phase (230 V). Many models with such a power supply can operate from a conventional outlet, which makes it much easier to connect. However, high power consumption (3.5 kW and above) requires connection to the mains via a distribution board .
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Three-phase (400 V). Power supply from 400 V mains is suitable for heat pumps of any power, including for models equipped with high-consumption heating elements. In addition, devices with such a supply during continuous operation consume less energy than single-phase devices of similar power consumption. Thus, this option can be envisaged even in heat pumps of low power. The disadvantage of three-phase mains is the necessity to ask for the help of a professional electrician to connect the unit.
Compressor
The compressor is the main element, the "heart" of the unit: it circulates the coolant through the heat pump circuits and transfers heat from outdoors to the room. Knowing the name of the compressor, you can find detailed information about it and find out some features of the heat pump as a whole. Note that the name is usually indicated if the device uses a high-end compressor, often an inverter one.
— Inverter. The presence of a compressor with inverter power control in the heat pump. Models without an inverter have only two modes of operation — either on or off; and the set intensity of heating/cooling is provided by turning the compressor on and off for certain periods. In turn, the principle of inverter control is to smoothly change the compressor power, which avoids constant switching on and off. It provides many advantages: minimal wear, no power surges and unnecessary load on the electrical mains, as well as a comfortable (low and stable) noise level.
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.
Supply t°C
The temperature in the flow pipe for which the COP is specified. See below for more details on this coefficient. And this temperature is the temperature of the heat carrier at pump outlet, 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
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.
