Heat from the earth can be used as an energy source in many ways, from large and complex power stations to small and relatively simple pumping systems. This heat energy, known as geothermal energy, can be found almost anywhere—as far away as remote deep wells in Indonesia and as close as the dirt in our backyards. Tapping geothermal energy is an affordable and sustainable solution to reducing our dependence on fossil fuels, and the global warming and public health risks that result from their use.
A much more conventional way to tap geothermal energy is by using geothermal heat pumps to provide heat and cooling to buildings. Also called ground-source heat pumps, they take advantage of the constant year-round temperature of about 10°C that is just 5 to 10 feet underground. Either air or antifreeze liquid is pumped through pipes that are buried underground, and recalculated into the building. In the summer, the liquid moves heat from the building into the ground. In the winter, it does the opposite, providing pre-warmed air and water to the heating system of the building.
Your energy consumption for heating will be lowered up to 75% with the use of NIBE geothermal heat pumps.
NIBE produces 15 different types of ground-source heat pumps, ranging from 5 kW to 40 kW. By using a cascade connection it is possible to achieve an output of 360 kW. The energy consumption for heating and hot water can be lowered by up to 75% in comparison to heating systems using fossil fuels.
Heat Pumps using the soil or groundwater as the heat source
In the evaporator (heat exchanger) the energy transfers from the cold medium to the refrigerant. The refrigerant will then evaporate. The refrigerant is transported in the circuit by the compressor to increase the pressure and temperature of the refrigerant. In the condenser (heat exchanger) the refrigerant cools and condenses. The energy is then transferred from the refrigerant to the heating system of the house, hot water system or air system The expansion valve regulates the mass flow of the refrigerant to maintain the pressure difference between the high pressure and the low pressure side.
During the summer, solar heat is stored in the soil. This is either directly absorbed as insulation or as heat from rain and the air from the near-surface layer of the soil. Using this energy for heating is a cost effective method. The highest yield can be obtained from soil with high water content. The heat is extracted from the soil by means of buried plastic tubing. An environmentally-friendly, non-freezing emulsion of water- and glycol circulates in the tubing. The soil above the earth collector may not be sealed off under any circumstances, i.e. by buildings, asphalt or concrete.
Earth collectors do not require a permit. Installation depth is approx. 20 cm below the local frost line.
Question / Answers
Can anyone have rock-/ground-/lake source heating?
It completely depends on the circumstances. If you have a rock shelf not too far beneath the surface of the ground it is no problem. If you have a large plot or fields around the house, ground source is a very good alternative because it is many times cheaper to install. If your house is near a lake and you have a lake plot with permission to use water source heating this is also a good alternative.
How deep must the collector be between the bore hole and the house?
The collector should be laid about 1 m deep and act as a ground collector on the way to the house. Incoming and outgoing pipes should be separated or insulated from each other.
Will the heat in my bore hole run out?
The heat that is taken from the ground comes from the sun’s rays and as long as the sun shines the ground is recharged during the summer months provided that the installation is correctly dimensioned. The ground operates as a gigantic battery where water conducts new heat into your bore hole.
We are a family of four, is the integrated water heater of 160 litres enough?
That completely depends on what your hot water consumption is as a family. In normal use 160 litres is fine for a family. If one has a jacuzzi that is used frequently one should perhaps consider either supplementing with an external hot water heater (Compact 200 type) or select an 11-model with external accumulator tank.
I have a pool, wood boiler and a solar panel. Can I use these together with the heat pump?
NIBE’s heat pumps and other products, such as boilers and hot water heaters, are designed to be compatible with lots of different products and operating conditions. NIBE recommends different solutions for dockings between different systems. These can be found in “Installation and Maintenance Instructions” which can be downloaded from the website. For special cases contact NIBE and we will help find the best solution.
How should one isolate the collector at the house?
The collector must be insulated for the last few metres (at least 2 m) to the house. This is to avoid freezing around the collector with frost ruptures as a result.
Why dimension with an immersion heater at the core, isn’t it better to have a more powerful compressor and therefore use less expensive electricity?
A heat pump is dimensioned for best operation and that is obtained if it is too little for the coldest days of the year (which is when the immersion heater kicks in) and just right for the rest of the year.
How many starts of the compressor is normal per day/year?
That varies quite a lot, it depends on how many hours the compressor runs in a year. Normal number of compressor hours is anything from 3000 to 4500 hours/year. As a result of this there are more starts if the hours are fewer. Likewise if the starts are fewer the hours are more. Normal number of starts is anything from 4000 to 16000 starts/year. There may be even more in special circumstances.
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