If you've been looking for a green source of heating and cooling, you probably know that geothermal HVAC is one of the most eco-friendly options commonly available today. But it can seem a little intimidating at first because it requires both a significant investment of money and a large amount of space. Fortunately, there are several types and variations of geothermal HVAC systems that you can choose from based on your needs and what you have available. Here are the basics of two different types.
1. Open loop system
This system is called "open loop" because the loop of piping that connects to the HVAC unit opens into a body of water (or source of groundwater) that gets pulled into the loop and carried to the unit for heat exchange. It then completes the loop by being carried back out to a discharge location (which could be back in the same body of water in some cases).
This is ideal for homeowners who have a body of water or source of groundwater that meets the requirements for an open loop system, but don't have the sheer space needed for a closed loop system. An open loop system can also be more affordable to install because there's not so much digging required. However, there are additional considerations such as treating the water to make sure it's clean enough that it won't clog or damage the system.
2. Closed loop system
This system has several variants available. Instead of using a water source, a closed loop system usually uses antifreeze (circulated in an underground closed pipe system to keep it the same temperature as the ground) and brings that up to the unit to exchange heat with it.
There are several variants on this system, which make it adaptable to different situations and budgets. For example, there's the question of horizontal versus vertical. A horizontal loop can be built in only a few feet of soil, but it does require a larger area of land to be dedicated to this purpose. A vertical loop requires deeper digging, which means you need deeper topsoil and a deeper wallet.
And your situation itself can also affect the price of your system. If your soil doesn't conduct well, you'll need more piping to get the same amount of heat transfer. If your soil is an excellent conductor of heat (for example, if it's a dense, wet clay) you won't need as much piping as you will for loose, gravelly dry ground.
These two basic types of geothermal HVAC systems can cover a wide range of land types and situations. And although they're both a large investment in eco-friendly living, there's a significant price variation as well.