Heat Pumps

Territory of the Czech Republic does not have very good conditions for the use of geothermal energy resources. The so-called high potential geothermal resources, allowing the use of geothermal heat directly for the generation of electricity or central heating sources, which are successfully used for example in Iceland or Italy, do not practically exist in our country.

In the Czech Republic, however, the low potential heat of the environment can be successfully used in the systems utilizing heat pumps. With the help of heat pumps the low potential heat is transferred to a higher temperature. Thus the heat produced can be used for heating buildings, heating the water, or for other purposes (water heating in the swimming pools, air conditioning heaters, greenhouses, etc.). With the help of heat pumps the "dry" heat from the earth's wells, the heat of warm surface layers of soil, the heat of groundwater and surface water, or outdoor air heat can be used.

Principles underlying the mechanics of heat pumps were described already in last century by English physicist lord Jelcin. The basic principle of heat pump is pumping heat from a lower to a higher temperature level using energy from outside. Basically reverse principle than for cooling equipment. Heat pumps unlike other devices utilizing renewable energy sources need for its operation energy supplied from outside. For most commonly used compressor heat pumps the energy used and supplied from outside is the electricity needed to drive the compressor.

Figure - Underlying principles of heat pump

Normal heat pumps now commonly supply twice to five times more heat than they consume electricity to drive the compressor. The ratio of thermal energy produced to the amount of driving energy, expressed in the same units, is called the coefficient of performance (COP) and is a fundamental characteristic of the heat pump. Typical values of COP are varying between 2.5 to 4.5 and today is not the exception COP exceeding value of 5.0. The closer the temperature of low potential energy source and heating circuit, the higher COP. Experience shows that one degree Celsius more of low potential heat as well as one degree Celsius less at the output of heat pump results in savings 2,5 % of energy necessary to drive the heat pump. It is clear that from the operational point of view it is best to combine heat pump with low temperature “classical” radiator based heating system (thermal gradient maximum 55/50 °C, lower would be even better), with floor heating (thermal gradient 35/30 °C), or combination of both. The heat pump is usually proposed for the so-called bivalent operation, ie. operation with a supplementary (bivalent) source, which may be, for example, electric or gas boiler, but also other sources controlled automatically. Down to a certain outdoor temperature, so called bivalence point (usually around 5 °C), the heat pump is operated as the sole source of heat. At lower temperatures, when the output of heat pump is not sufficient, supplementary source of heat is switched on. Properly proposed heat pump covers approximately 95% of annual heating needs.

Heat Pumps Water-Water
Heat Pumps Soil-Water
Heat Pumps Air-Water or Air-to-Air