A passive heat pump cooling system can save you hundreds of dollars annually in cooling costs, but they are expensive to purchase and install.
1 - Understanding Geothermal Heat Pumps
Geothermal heat pumps use passive cooling to lower the temperature of your home. Passive cooling is the most economical way to reduce temperature. These heat pumps tap into the temperature regulating properties of the earth. Once you go below a certain depth, the temperature is constant and comfortable. Geothermal pumps use collector loops to gather the cooling (or heating) properties of the area passively, or without using additional energy. The pump needs energy only to circulate air, but it doesn't have to work hard to cool or heat the air, the earth does that all by itself. Because of the low wear on passive systems, they usually last more than twenty years, and are virtually maintenance free. Understanding the principles of passive heat pumps will help you to set up your own system.
2 - Types of Loops
The liquid loops are drilled underground to collect the thermal benefits of passive temperature regulation. There are two primary types of loops. Horizontal loops, which are used in areas where there is plenty of land available for loops ranging from 100 to 500 feet in length, and vertical loops, which are used in areas with a limited surface availability. Vertical loops require drilling between 100 and 300 feet deep. While you can install the heat pump itself, setting up the underground loops is a task that can only be completed by a licensed professional.
2 - Selecting a System
Heat Pumps use rating systems called SEER to determine energy efficiency. SEER stands for 'seasonal energy efficiency ratio'. This rating measures the effective output of your pump in terms of the energy needed to power it. The higher the SEER rating, the more efficient your heat pump is and the lower your bills will be. Choose a heat pump with a SEER rating of at least 14.5 to maximize the efficiency of your unit. When considering which loop system to use, the type of material (rock, soil, and so forth) that exists under your plot will be a consideration, and so will the surface area of your plot. If you have access to a pond, you are lucky: you may be able to install your passive heat pump cooling system through the pond, and avoid the hassle of having liquid loops drilled.
3 - The Cost of Installation
Upfront installation costs for geothermal heat pump systems can be very expensive. This is because of the drilling and equipment required to run the cooling loops. If you install a pond-based system, you will save substantial money. That said, expect to spend anywhere from $7,500 to $15,000 to install this particular type of heating and cooling system. Remember, though, that the system is extremely low-maintenance, and that the savings you will see on your energy bills will recoup the difference for you in an average of 2 to 7 years. For a system that lasts 20 years or more, this is a good long-term investment.