Wednesday, November 25, 2015
Geothermal heating systems explained and evaluated
Geothermal heating systems use the constant earth temperature at deeper levels of 6-10 metres, unaffected by surface temperatures, to provide heat. In summer, they cool and the heat extracted from the air is carried deep into the ground for use in winter months.
There's 3 three common systems:
1. Vertical closed-loop geothermal heat systems have a pump circulating an antifreeze solution through a closed loop buried underground or submerged in water. The continuously circulating fluid allows a heat exchange through conduction and, as the liquid surfaces, it's hot in winter or cool in summer and heats/cools as appropriate.
2. Horizontal closed-loop systems are similar but pipes run back and forth 3-8 feet underground in excavated trenches. These systems are usually less expensive to install but require more space and can be less efficient than vertical loop systems as they're affected by varying surface temperatures.
3. Open-loop systems operate by using ground water pumped straight from a supply well to extract and inject the heat. There are 2 wells and water's pumped from the first then, after the heat has exchanged, it's injected back into the second. Open-loop systems are thermally efficient and installation's cheaper but they're unsuitable for urban areas as a good source of ground water's needed.
Geothermal systems aren't cheap to install so are better for commercial premises or multiple residential properties. This is an advanced technology but, for the average family home, better value for money is investment in insulation.