Geothermal Heating and Cooling - An Introduction

Geothermal heating and cooling is in step with the times – and with the future. “Green” technologies – which work with the environment instead of against it – 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 saving money and protecting the environment in all 50 states and around the world.

As the area’s geothermal experts, Princeton Air will come to your home, evaluate your heating and cooling needs, and advise you about which geothermal heat pump will work best for you.

Geothermal Basics

How does a geothermal heating and cooling system work? Outdoor temperatures fluctuate with the changing seasons but underground temperatures don’t. Four to six feet below the earth’s surface, temperatures remain relatively constant year-round. A geothermal system capitalizes on these constant temperatures to provide “free” energy. In winter, a series of fluid-filled underground pipes called a “loop” absorbs stored heat and carries it indoors. The indoor unit compresses the heat to a higher temperature and distributes it throughout the building. In summer, the system reverses, pulling heat from the building, carrying it through the earth loop and depositing it in the cooler earth.

What Makes A Geothermal System Different From Ordinary Systems?

Unlike ordinary 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, 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.

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What Are The Components Of A Geothermal System?

The three main parts consist of the geothermal unit, the underground piping system (open or closed loop), and the ductwork.

How Efficient Is A Geothermal System?

A geothermal system is over five times more efficient in heating and more than twice as efficient in cooling as the most efficient ordinary system. Because geothermal systems move existing heat rather than creating it through combustion, they provide four to five units of energy for every one unit used to power the system.

Do Geothermal Systems Require Much Maintenance?

No. Geothermal systems are practically maintenance free. The buried loop will last for generations. The unit’s fan, compressor and pump is housed indoors, protected from the weather and contamination. Usually, periodic checks and filter changes are the only required maintenance. While WaterFurnace does offer an outdoor geothermal unit for jobs where space is limited, its rugged housing is sealed so that no components are exposed to the elements.

What Does Geothermal Mean For The Environment?

Geothermal systems work with nature, not against it. They emit no greenhouse gases - which have been linked to pollution, acid rain and other environmental hazards. WaterFurnace’s earth-loop antifreeze will not harm the environment in the unlikely event of a leak. And all of the current WaterFurnace product lines use R-410A or R134a, both of which are performance-enhancing refrigerants that will not harm the earth’s ozone layer.

How Does A Geothermal Heat Pump Work?

Heat pumps don’t create heat. They take existing heat and move it. Anyone with a refrigerator has witnessed the operation of a heat pump. Refrigerators collect heat from the unit’s interior and move it to the exterior for cooling purposes. Unlike a refrigerator, a heat pump can reverse itself. An air-source heat pump, for example, can extract heat from outdoor air and pump it indoors for heating purposes.

A geothermal heat pump works the same way, except that its heat source is the warmth of the earth. The process of elevating low-temperature heat to over 100°F and transferring it indoors involves a cycle of evaporation, compression, condensation and expansion. A refrigerant is used as the heat-transfer medium which circulates within the heat pump. The cycle starts as the cold, liquid refrigerant passes through a heat exchanger (evaporator) and absorbs heat from the low-temperature source (fluid from the ground loop). The refrigerant evaporates into a gas as heat is absorbed.

The gaseous refrigerant then passes through a compressor where the refrigerant is pressurized, raising its temperature to more than 180°F. The hot gas then circulates through a refrigerant-to-air heat exchanger where heat is removed and pumped into the building at about 100°F. When it loses the heat, the refrigerant changes back to a liquid. The liquid is cooled as it passes through an expansion valve and begins the process again. To work as an air conditioner, the system’s flow is reversed.

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. With a simple flip of a switch on your indoor thermostat, you can change from one mode to another. In the cooling mode, a geothermal heat pump takes heat from indoors and transfers it to the cooler earth through either groundwater or an underground earth loop system. In the heating mode, the process is reverse.

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Can A Geothermal System Also Heat Water?

Yes. Some geothermal heat pumps can provide all of your hot water needs at the same high efficiencies as the heating/cooling cycles. An option called a hot water assist can be added to most heat pumps. It will provide significant savings by heating water before it enters your hot water tank.

Do I Need Separate Earth Loops For Heating And Cooling?

No. The same loop works for both. To switch heating to cooling or vice versa, the flow of heat is simply reversed.

Does The Underground Pipe System Really Work?

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 and more durable pipe materials have been combined to make geothermal heat pumps the most efficient heating and cooling systems available.

What Is A Closed Loop System?

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.

How Long Will The Loop Pipe Last?

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.

How Deep Or Long Will My Trenches Be?

Trenches are normally four to six feet deep and up to 400 feet long, depending on the number of pipes in a trench. One advantage of a horizontal loop system is being able to lay the trenches according to the shape of the land. As a rule of thumb, 500-600 feet of pipe is required per ton of system capacity. A well-insulated 2,000 square- foot home would need about a three-ton system with 1,500 - 1,800 feet of pipe. Loop lengths and depths may vary with loop type, soil conditions and climate.

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If you want to reduce your energy costs, and do something good for the environment by switching to a clean energy source, geothermal is the way to go and Princeton Air can get you there.

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Can A Geothermal Heat Pump Be Added To My Fossil Fuel Furnace?

Split systems can easily be added to existing furnaces for those wishing to have a dual-fuel heating system. Dual-fuel systems use the heat pump as the main heating source and a fossil fuel furnace as a supplement in extremely cold weather if additional heat is needed.

Is A Geothermal Heat Pump Difficult To Install?

Most units are easy to install, particularly when they replace another forced-air system. They can be installed in areas unsuitable for fossil fuel furnaces because there is no combustion, thus no need to vent exhaust gases. Ductwork must be installed in homes that don’t have an existing air distribution system. The difficulty of installing ductwork will vary and should be assessed by a contractor. Another popular way to use geothermal technology is with in-floor radiant heating, in which hot water circulating through pipes under the floor heats the room.

Do I Need To Increase The Size Of My Electric Service?

Geothermal heat pumps don’t use large amounts of resistance heat so your existing service may be adequate. Generally, a 200-amp service will have enough capacity, and smaller amp services may be large enough in some cases. Your electric utility or contractor can determine your service needs.

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Barbara and George live in a 1950’s Cape Cod style home in Princeton. The home had been taken care of for many years, but needed a number of... Read More