How Geothermal Heat Pumps Works Learn how and why a WaterFurnace saves you money

Geothermal heat pumps are not only the most comfortable way to heat and cool, they’re also the most cost effective. They’re versatile enough to excel in almost any home or environment, and you’ll find geothermal systems in more than 1 million households across Canada and all 50 U.S. states. They can be scaled for any applications—from single-family homes to entire college campuses. In fact, WaterFurnace heats and cools their entire 110,000 square-foot headquarters with WaterFurnace geothermal equipment. Here are a few reasons why geothermal is one of the fastest growing technologies available in the HVAC industry:

An Introduction

Geothermal heating and cooling is in step with the times – and with the future. Green technologies continue to gain momentum amid concerns over the skyrocketing cost of fossil fuels and energy conservation. Geothermal technology is proven, reliable, and safe. It significantly reduces energy usage and utility bills for homeowners and business owners. Millions of geothermal systems are currently operational across the world. We’ve prepared this booklet to answer questions about how geothermal systems work and how you can benefit from going geothermal.

Geothermal Basics

Outdoor temperatures fluctuate with the changing seasons, but underground temperatures do not. Four to six feet below the earth’s surface, temperatures remain relatively consistnt year-round. A geothermal system capitalizes on these stable temperatures to provide energy. In the winter, a series of fluid-filled underground pipes called a “loop” absorb heat from the earth and carry it indoors. The indoor unit compresses the heat to a higher temperature and distributes it throughout the building. In summer, the system effectively works in reverse, pulling heat from the building which is then carried outside and re-distributed into the earth.

What makes a Geothermal system different from ordinary systems?

Unlike ordinary heating systems, geothermal systems don’t burn fossil fuel to generate heat; they simply transfer heat to and from the earth to provide a more efficient, more affordable, and environmentally friendly method of heating and cooling. Typically, only a small amount of electricity is used to operate the unit’s fan, compressor and pump.

Does a Geothermal system heat and cool?

One thing that makes a geothermal heat pump so versatile is its ability to be a heating and cooling system in one unit. With a simple flip of a switch on your indoor thermostat, you can change from heating to cooling. In the cooling mode, a geothermal heat pump takes heat from indoors and transfers it to the cooler earth through groundwater or an underground earth loop system. In the heating mode, the process is reversed.

What types of loops are available?

There are two main types: open and closed. The buried pipe, or earth loop, was an important technical advancement in heat pump technology. The idea of burying pipe in the ground to gather heat energy originated in the 1940’s. New heat pump designs, along with more durable pipe materials have been combined to make geothermal heat pumps the most efficient heating and cooling systems on the market.

An open loop system uses groundwater from an ordinary well as a heat source. The groundwater is pumped into the unit where heat is extracted and the water is disposed of in an environmentally safe manner. Because groundwater is a relatively constant temperature year-round, wells are an excellent heat source.

A closed loop system uses a continuous loop of buried polyethylene pipe. The pipe is connected to the indoor heat pump to form a sealed, underground loop through which an environmentally friendly antifreeze-and- water solution is circulated. A closed loop system constantly recirculates its heat-transferring solution in pressurized pipe, unlike an open loop system that consumes water from a well. Most closed loops are trenched horizontally in areas adjacent to the building. However, where adequate land is not available, loops are vertically bored. Any area near a home or business with appropriate soil conditions and adequate square footage will work.

Closed loop systems should be installed using only high-density polyethylene pipe. Properly installed, these pipes can outlast the house. They are inert to chemicals normally found in soil and have good heat conducting properties. PVC pipe should never be used.

Closed loop systems can also be vertical, where the loop is contained in vertical boreholes in the earth, mostly used for plots of lands that don't have as much square footage. The depth of the boreholes is generally about 250 ft. per ton of heat pump capacity, however this will vary based on where your installation is located. After the U-shaped loops are inserted into the boreholes, they are grouted to ensure consistent contact with the earth.

Loops can also be installed in bodies of water if they are deep enough. Due to water levels changing throughout the year based on weather conditions, a minimum depth of 6 feet is required at its lowest yearly level in order for a loop installation to be considered. The amount of surface area required for the water body depends on the heating and cooling requirements for that specific system. You should opt against using water from a spring, pond, lake or river as a source for an open loop system unless it’s proven to be free of excessive particles and organic matter, as particulates like these can clog the system in a short period of time, making it inoperable.