Geothermal underfloor heating is a system employing the use of underfloor piping to heat a desired space such as rooms in a building or residence. Hot water is pumped through the pipe network, utilizing the constant temperatures of of a geothermal hot spot to heat the fluid. The water warms the floor it runs under, and the floor in turn heats the room or space desired.
The primary difference between geothermal and other types of underfloor heating is the method in which the water piped through the floor is heated. Standard systems use a boiler where the pipes are placed to exchange heat between the steam and the water as efficiently as possible. In a geothermal system, a pump is used to drive the water through the system, a pump is used to drive the water through the system. Instead of a boiler, however, the copper pipes are placed underground, in a location where the temperature is constant year round and suitable for use. This temperature can vary depending on availability and individual needs, although generally higher temperatures lead to more efficient systems. As the water is forced through the ground, it exchanges heat with the warmer earth. The heated water then travels throughout the underfloor pipe network. As the hot water travels through the floor, it exchanges heat with the colder room. Heat from the water first travels to the outside of the pipe, then conducts into a material called screed, conducts through the floor of the room, and through natural convection heats the desired space.
There are three different types of geothermal sources which can be used to heat water underground; horizontal, bore hole, and ground water heat sources. The horizontal heat source will heat water to a constant temperature throughout the year but will require more excavation. Bore hole heat source will not have a constant temperature year-round but will require less excavation and less piping than the horizontal heat source. Ground water heat sources are open loop sources and require that you have a heated water source available to you but would require the least amount of piping of the three types of heat sources and the temperature should be uniform year-round if the depth of the source is great enough. Each of the three types of sources have their own advantages and disadvantages. The heat source would be selected depending on funds and the resources which are available.
Underfloor heating is an excellent way to heat a building. It provides a very uniform heat distribution causing the entire building to be approximately the same temperature. This system is installed under the floor as seen in the cross-sectional image below showing all the different layers of materials used to provide the best results. The vaporous barrier and the insulation which are placed at the side walls and below the concrete in which the pipes are laid ensures that very little heat is lost below the floor and to the outside of the building. The piping most commonly used in underfloor heating systems are cross-linked polyethylene (PEX) pipes. The PEX pipes are perfect for the pressures and temperatures of water at which the system will be operating. These pipes are very long lasting and require practically no maintenance.
There are many advantages to using a geothermal underfloor heating system. First the system requires very little energy to function and maintenance is very low, which means that energy costs as well as maintenance costs will be very low. It offers an even distribution of heat throughout the space to which it is providing heat. None of the equipment is exposed making for an aesthetic appearance and also keeps the equipment safe from vandalism. Most geothermal underfloor heating systems are 48% more efficient than gas furnaces and 75% more efficient than oil furnaces. The system is very quiet while most common heating systems can be very noisy. Also the system can generate hot water to be supplied to the building at no cost during the summer and very little cost during the winter.
The greatest disadvantage of this system is that the initial cost of parts and installation is much greater than radiant or circulating air systems. This is because excavation work is necessary to bury the pipes at the appropriate depth where the temperature will remain approximately constant year-round and the quantity of pipes necessary running underground and underfloor. A disadvantage of the open loop system of the ground water heat source is that it is subject to potential clogging and corrosion.