school energy&environment

What is a heat pump?

A heat pump is an instrument which allows heat exchange between a source of energy (for example the ground but also the air of the atmosphere or the water of the ground water table) and an environment with a different temperature.
It works like refrigerator, and can work both ways (for heating in winter or for cooling in summer). A heat pump absorbs heat from the “vector” fluid in the probes, through evaporation in an evaporator, after which the temperature is increased using a compressor that releases heat into the surrounding environment through a condenser, and is connected to a distribution system that distributes heat all around the home. In a domestic geothermal installation, the heat pump can increase the water temperature from 8 – 12° C of the vector fluid to about 35 – 40°C of the water that circulates in the radiant panels of the distribution system; however water temperature can be increased to much higher temperatures (approximately 70°C) if the system uses radiators. In summer, instead, water temperature for the air conditioning can be 8 – 10 °C lower than the temperature of the environment.
During this process the heat pump uses electricity, however modern heat pumps are extremely efficient systems with a very high performance, that can produce much more (thermal) energy than the (electric) energy that is consumed. The heat pump’s performance is indicated by “COP”, coefficient of performance, that is to say the ratio between energy produced and energy consumed. In modern pumps, COP is about 4 or 5: this means that with1 kW of electricity it is possible to obtain 4 to 5 kW of thermal energy.
The heat pump’s performance is inversely proportional to the difference in temperature between the source of energy (in this case the subsoil) and the environment to be heated (or to be cooled): the greater the difference in temperature, the lesser the performance of the heat pump will be, and therefore the greater the electricity consumption will be. For this reason low temperature radiant panels are preferable (in the floor or in the wall) to the radiators, and for the same reason geothermal heat pumps are more efficient than those using heat of the air outside as a source of heat (which is much colder than the subsoil: if the air temperature is less than -5°C, air heat pumps do not work).
A heat pump for a home of approximately 100 m2 is more or less as big as a fridge, and just as noisy, no exhaust gas or fumes are produced, no oxygen from the air is burnt (as in the case of common heating system burners) and therefore can be installed safely also inside homes. Heat pumps last about 15 years, just like heating system burners.