Geothermal systems include three major investments that need to be considered. First, a properly sized distribution or duct system needs to be installed. This should last a lifetime, but as we have found out, most ductwork is made of compressed fiberglass duct board. Compressed fiberglass duct board is prone to breakdown and leaking due to improper installation. It tends to get wet due to improper dehumidification and it is almost impossible to clean.
The second system is the underground heat or cooling source. Some use well water that pumps out of the ground at a constant temperature of around 55’. These wells then dump outside or back into another well. These systems are the most efficient, but can waste massive amounts of ground water, which is a limited natural resource. These systems can have maintenance issues depending on the water quality and hardness. Many have to change their water filters on a regular basis.
Most systems have what we call a closed loop. Closed loops can be a major investment due to the cost of excavation and drilling. These recirculate a solution of water and antifreeze through an underground piping system. The ground can be about 55’, so it is an ideal way to heat and cool efficiently. We do find systems that lose efficiency due to the ground over heating in the summer, but more often over cooling in the winter which can cause the loss of capacity and comfort.
No one knows for sure how long a closed loop system should last. These consist of a non-corrosive plastic pipe that can wear out from the outside at any time.
The third part of the system is the machine that comes as a single unit. Most geothermal systems are sized for heat and have one speed; high. This can cause discomfort in the summer months when dehumidification is needed. Ground source heat pump machines are typically more expensive than standard systems. They last for about the same amount of time as most appliances, depending on how often they need to cycle the air duct system and also the heat exchange medium they use.
New Geothermal systems can be two speeds which can help with the dehumidification, but also add to the investment. Variable speed technology will make geothermal super-efficient and deliver high comfort when modern technology is applied in the near future.
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