In the past few weeks, we have talked about geothermal heat pumps (GHPs) and their benefits. This week, we will discuss the four main types of geothermal heat pumps – horizontal, vertical, pond/lake, and open-loop – and the advantages and drawbacks of each one. Choosing the best option for your home requires looking at several variables, including: the climate, soil conditions, available land, and local installation costs at the site.
Horizontal (Closed-Loop System)
Typically used for residential projects, horizontal geothermal heat pumps require sufficient land and trenches at least 4 feet deep. The most common layouts either use two pipes, one buried at six feet, and the other at four feet, or two pipes placed side-by-side at five feet in the ground in a two-foot wide trench.
Vertical (Closed-Loop System)
This type of GHP is typically used for commercial buildings and schools. For a vertical system, holes (approximately four inches in diameter) are drilled about 20 feet apart and 100–400 feet deep. . Into these holes go two pipes that are connected at the bottom with a U-bend to form a loop. The vertical loops are connected with horizontal pipe (i.e., manifold), placed in trenches, and connected to the heat pump in the building.
Pond/Lake (Closed-Loop System)
Perhaps the lowest cost option (if your site has a sufficient body of water nearby). A supply line pipe is run underground from the building to the water and coiled into circles at least eight feet under the surface to prevent freezing. The coils should only be placed in a water source that meets minimum volume, depth, and quality criteria.
This system uses well or surface body water as the heat exchange fluid, circulating directly through the GHP system. Once it has circulated through the system, the water returns to the ground through the well, a recharge well, or surface discharge. This option is obviously practical only where there is an adequate supply of relatively clean water, and all local codes and regulations regarding groundwater discharge are met.
So which system best suits your needs? Contact a professional to help better assess your situation.
If you have any questions, Fresh Air Concepts can help. Call 1-800-708-4FAC or click here today!
For more information on the subject, read this article from EnergySavers.gov