Frequently Asked Questions

What does “coefficient of performance” mean?

This is a main characteristic for any heat pump machine. It can be defined in two ways:

  • for obtaining an average value (e.g., within a heating season) the ratio of the received energy (heat, kWh) to the energy input (typically electricity, kWh) for a certain period of time is calculated. The longer the period is, the more accurate the value of the coefficient of performance is.
  • for obtaining a current value, the ratio of the power of heat flow obtained in the present moment (or in specified temperature parameters), to the input electrical energy for operation of the compressor, circulator pumps and all powered elements which have a direct connection with the operation of the whole heat pump installation is calculated.

Theoretically, the coefficient of performance can reach a value over 10.0. In practice, the value of this coefficient for the most widespread household heat pump installations varies in a range between 2.0 and 5.5. This means that for every 1.0 kWh input, 2.0 to 5.5 kWh heat can be generated.

Where do we “get” heat?

Natural resources – air, water and soil can be used as the biggest inexhaustible, low-temperature heat sources. Their temperature changes during the different seasons or during the time when it is required to obtain heat for heating purposes.

How do we take the heat from low-temperature sources?

There are two methods for taking the heat , depending on the type of the heat pump unit, type of heat source and the method of carrying it – direct and indirect heat exchange. The difference between both is whether an intermediate working fluid, between the heat source and heat pump unit, that transfers the heat exists.

How does increasing the temperature level of the heat work?

The process is carried out by the popular to thermodynamics “Reverse Carnot cycle”. In contrast to internal combustion engines, steam turbines, etc. which convert the fuel energy in mechanical work (movement), its mechanical work transfers heat while also increases its temperature level. The generated higher temperature is a result of increasing the density of a working substance (gas of vapor). Most often the increase of density is performed with the help of a compressor.

How high temperatures can we get?

It is recommended the temperature does not go over 55 °С. This limitation is a result of many factors – the restriction of the operation of the compressors and elements of the whole installation, efficiency of the entire heat pump unit and other technical parameters and restrictions. Trends in the development of modern heat pump units allow use of low-temperature heating units and installations that increase the effective use of heat pumps significantly.

Is the installation of a heat pump expensive?

Taking into account all aspects of a heat pump installation – heating and hot water for domestic use, the option to use its cooling ability in the hot summer months, the ability to fully automate the operation process – overall, creating comfort, you can safely say that it is not expensive. The price for building a heat pup installation is comparable to the price of, for example, building a fully-automated heating installation with a biomass or petrol boiler, with the difference that the latter two can’t “cool you down” in the summer.

What will my expenses for heating and hot water be?

The analysis we made on one of our heat pump installations showed that the price for 1.0 kWh heat generated by a heat pump unit is 0.03 lev. In the near future we will provide updated information for our other heat pump installations, as well as analysis of the price of heat generated from other heat sources.

What is the time for return of this investment?

This question can not be answered unequivocally, because it depends on how you do the comparison, what type of fuel will be compared, the degree of automation of the process, is there any "human factor" interference - for example, adding boiler coal daily. There are many approaches to carry out such an analysis, and there are software products that enable accurate calculation of return on such an investment.