How Geothermal Heat Pumps Work

No matter what climate you live in, the temperature throughout the year varies. For some climates that means blazing summers that cool to frigid winters. What many people don't realize is that the temperature below ground (regardless of climate or season) stays fairly consistent all year.

The ground is able to maintain a higher rate of temperature consistency because it absorbs 47% of the suns energy (heat) as it hits the Earth's surface. Geothermal (also called ground source) systems are able to tap into this free energy with an earth loop. This technology is then used to provide your home or office with central heating and cooling.

How to apply for a permit to use a geothermal loop in the ocean or a lake

You need to apply with the provincial government via Frontcounter BC. They have offices in various towns.

www.frontcounterbc.gov.bc.ca

Click to learn:

• How a geothermal heat pump works.
• About Loop Designs
• Geothermal System Benefits
• Geothermal System Applications
• How much money a heat pump can save
• Frequently Asked Questions
• Geothermal Tubing Prices

Click to view:

• Actual installations
• Geothermal Journal (pdf) - in-depth articles on geothermal heating

Earth Loop Designs

The earth loop transfers heat to and from the ground - eliminating the need for fossil fuels. It's the heart of a geothermal system, and its biggest advantage over other heating and cooling technologies. Earth loops come in two basic types. Closed loops, made of durable, high-density polyethylene pipe, are buried in the earth or submerged in a lake or pond. They transfer heat by circulating refrigerant. Open loops use ground water pumped from a well as a heat source.

The type of loop to use depends on the terrain, the cost of trenching or drilling, the availability of quality ground water and available space.

Horizontal Trench Loops

Often used when adequate land surface is available. Depending on system needs and space available, pipes are placed in trenches that range in length from 100 to 400 feet. A typical home requires 1/4 to 3/4 of an acre for the trenches.

Horizontal Slinky Loops

A trench is dug with a backhoe several feet deep and about 3 feet wide. The coils are "laid off" and spaced evenly throughout the trench. Trench lengths are typically 100 to 150 feet long. Slinky loops are great space savers.

Vertical Loops

The ideal choice when available land surface is limited. Well drilling equipment is used to bore small-diameter holes from 100 to 400 feet deep.

Pond Loops

Very economical to install when a large body of water is available. Coils of pipe are simply placed on the bottom of the pond or lake. Less pipe is used than in an earth loop because water is a better conductor of heat energy. Pond loops are a cost effective way to install the loops as trenching is limited.

Open loops (Well-Water Systems)

In ideal conditions, an open-loop application can be the most economical type of geothermal system. These use groundwater from a well as a direct energy source.

Geothermal System Benefits

Lower Operating Cost - A geothermal system operates more efficiently than other heating and cooling systems because they can deliver four units of energy for every one unit of electrical energy used. That translates into an efficiency rating of 400%, compared to the most efficient gas furnace, which rates 94%.

Enhanced Comfort - During heating you'll experience warm air without the hot blasts associated with ordinary gas furnaces. Compared to an air source heat pump, the air is warmer from a geothermal system. For ultimate comfort, a zoning system can be added using multiple thermostats to precisely control temperatures in various zones.

Safe - Because natural gas, propane or oil are not required to operate a geothermal unit, there's no combustion, flames or fumes and no chance of carbon-monoxide poisoning.

Clean - No fumes are produced during operation By adding optional high efficiency air cleaners, you'll achieve high levels of indoor air quality.

Quiet - Unlike air source heat pumps, there is no noisy outdoor unit. Geothermal heat pumps are designed and constructed for "whisper quiet" operation.

Reliable - Unlike air source heat pumps, geothermal units are installed indoors so they are not subject to as much wear and tear caused by the elements.

Environmentally Friendly - Geothermal systems are the most environmentally friendly way to heat and cool your home. The system emits no greenhouse gasses.

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Geothermal can be installed in a wide variety of installations - new or old homes, large or small. They can also be used for installations other than forced air.

Radiant in-floor heating - Geothermal systems can provide hot water for radiant floor applications. Tubes filled with water are installed under tile, wood, linoleum or stone floors. The heated water provides consistent comfort throughout the room. It is even possible to take it outside to encourage snow melt from driveways and patios. Click here for more information on radiant heat.

Domestic Hot Water - A geothermal system can provide some or all of your hot water at higher efficiencies, offering additional energy savings. A geothermal unit will deliver hot water to your tank during the heating and cooling modes. In fact, the heat removed from your home during cooling is deposited into your water heater providing you with virtually free hot water.

Pool Heating - Units can also be uses to pools, spas and hot tubs using much less energy than an ordinary pool heater.

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How Much Money Can I Save with a Heat Pump?

The following figures are a rough guide for comparing heating sources and applications. The cost figures are as of April 2011 for Victoria, BC. The figures below are based on a home of approximately 2,000 square feet and are in Canadian dollars.

*Propane furnace @ 70% efficiency
**Oil furnace @ 60% efficiency
^Electric furnace @ 100% efficiency
^^Air source heat pump @ 2.5 COP

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Frequently Asked Questions

Q. What are the components of a geothermal heat pump system?
A. The three main parts are the heat pump unit, the liquid heat exchange medium (open or closed loop) and the air delivery system (ductwork). The unit's main components are the compressor, heat exchanged, air coil, blower motor and electrical controls.

Q. Is a geothermal heat pump difficult to instal?
A. 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.

Q. Do I need to increase the size of my electric service?
A. Geothermal heat pumps don't use large amounts of power so your existing service may be adequate. Generally, a 200-amp service is required.

Q. Can a geothermal heat pump be added to my fossil fuel furnace?
A. 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.

Q. Do I need a back-up heat supply?
A. Geothermal systems used in climates where temperature drop below freezing are generally installed with an auxiliary back-up heater. Your contractor can help determine the most appropriate size system.

Q. How are the pipe sections of the loop joined?
A. Pipe sections are joined by thermal fusion using a fusion tool heated to 500°F. This technique creates a secure connection to protect from leakage and contamination.

Q. If the loop falls below freezing, will it hurt the system?
A. No. The antifreeze in the loop will keep it from freezing.

Q. Can I reclaim heat from my septic system disposal field?
A. No. Such usage is banned in many areas.

Q. Does an open loop system cause environmental damage?
A. No. They are pollution free. The heat pump merely removes or adds heat to the water.

Q. With an open loop system, what problems can be caused by poor water quality?
A. Your water should be tested for hardness, acidity and iron content before a heat pump is installed. Mineral deposits can build up inside the heat pump's heat exchanger. A treatment system may be recommend to improve water quality and extend your equipment's lifetime.

Q. Can I install an earth loop myself?
A. Properly designing and installing an earth loop requires extensive training. In order to obtain optimum system performance, the earth loop size, design and configuration need to be carefully considered.

Q. Will an earth loop affect my lawn or landscape.?
A. The actual process of installing the loop will disturb the surface to some degree. With proper restoration, most loop fields are "invisible" after a couple of months After the initial installation, the loop will have no effect on grass, trees or shrubs. Nor will roots from trees cause a problem with the pipe.

Q. How long will the loop pipe last?
A. Closed loop systems should be installed using only high-density polyethylene pipe. This pipe does not rust, rot or corrode and is inert to chemicals normally found in soil. Actual life expectancy of the pipe is over 200 years. Copper or PVC pipe should never be used.

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All prices are in Canadian dollars and are subject to change without notice. Prices may be applicable to state/provincial taxes. Shipping/freight charges may apply.