Geothermal FAQ

What is a geothermal/geoexchange heat pump?

A geothermal system is an electrically powered home comfort system that uses the earth's stored energy to heat or cool your home or business.

How does geothermal work?

The principles of a geothermal system are the same as a normal heat pump. The geothermal system simply moves heat from one place to another. The geothermal system moves the heat from the earth to your home in the winter and moves the heat from you home back to the earth in the summer.

How can a geothermal system transfer heat?

Earth has the ability to absorb and retain heat. In the winter, heat is extracted from the earth using water or an antifreeze solution. In the summer, heat is sent back to the earth through the same water or antifreeze that brought the stored heat to your home in the winter. The operation of the geothermal system (or any heat pump) is simply reversed to get the desired effect of heating or cooling.

 

How does geothermal know when to heat and when to cool?

That is done through the same basic thermostat you have used for years. A simple switch and temperature setting from your indoor thermostat determines the amount of heating or cooling.

What methods are available to transfer the water?

Open loop and closed loop are the two basic methods of moving the water or antifreeze.

What is a closed loop system?

Closed loop means that there is one continuous loop of special material used to transfer the water or antifreeze solution from the geothermal unit down into the earth and back to the geothermal unit. The water is being recirculated in a pressurized pipe instead of adding new water.

Where can I put this loop?

Depends on the amount of space available on your property. You can place the loops horizontally if there is a lot of land or you can place the loops vertically if the amount of land is limited. A pond or lake can even be used in some situations.

 Which geothermal loop is best?

There really isn't a "best" loop configuration for every geothermal system. Best in some areas is the vertical loop where drilling is easy and inexpensive. Some rockier areas may be better suited for horizontal looping. A pond or lake may be close enough to use for some geothermal jobs.

 

How much pipe is used for the loops?

There again, it depends on the particular area you are putting the geothermal system. A horizontal loop system normally needs 400 - 600 feet of pipe per ton. This pipe is buried in trenches normally 4-6 feet deep. The vertical loop normally takes 150 - 250 feet of pipe per ton. A hole is drilled and the loop is placed in the hole with a U-Bend to allow the water to circulate.

What kind of material is used for these loops?

Many different materials have been used in the past with different degrees of success. Currently, polyethylene is the most widely used material for looping. This pipe is also known as HDPE.  PVC should never been used for any of the closed loop piping in the ground.

How does HDPE loops get connected together?

The most common method of connecting piping is through heat fusion. Most fusion is done around 510 degree's Fahrenheit using special tools and irons just for geothermal piping. Barbs, screw fittings, clamps and glued joints are not recommended (especially if buried).  Many do-it-yourself kits use compression fittings made for HDPE.  This is an easy method for transitioning to HDPE pipe if you don't have fusion tools.

Will the loops be visible or affect my lawn?

The loops shouldn't be visible and will not effect your lawn. Initial installation will affect your lawn but will not be visible once the grass has grown back.

What about geothermal pipe freezing?

Antifreeze is used for climates needing freeze protection.

Can I do the loops myself?

Certainly! Poor installation can result in unsatisfactory performance and possible shortened equipment life so be sure to do your homework.

What kind of life do I get with the geothermal loop?

50 - 55 years is the standard on the loop if the geothermal system is installed properly.

How big are the pipes?

Normally, ¾" for the actual loop itself and 1¼" pipe going from the geothermal unit to the loop field. This area is called a header pit where the 1¼" ties into the ¾."

 

How much water is in the loops?

¾" pipe takes .028 gallons per foot. An average three ton loop would take approximately 40 gallons.

What kind of temperatures can I expect in a closed loop system?

Temperatures range from the 40's in the northern states to the upper 90's in the more southern states.

What are the drawbacks to closed loop systems?

Cost is the main drawback to closed loop systems. Drilling can be expensive in some areas of the country.

What about using an open loop instead of a closed loop?

Open loop geothermal systems have been used for years. Many areas no longer allow open loop geothermal systems saying they are bad for the environment since they may delete water supplies. Open loops are actually a great source of heat transfer since ground water stays relatively the same temperature year round.

What are the drawbacks to open loop systems?

The main drawbacks are the amount of wasted water since 6 - 9 gallons is normal for an open loop system. Possible mineral deposits can ruin a geothermal system causing major repair bills.

How hard is it to install a geothermal system?

The difficulty varies from home to home. New construction is the easiest as long as there is coordination between the homeowner, the builder, and the mechanical contractor. Space is the only real drawback to installing geothermal equipment since everything is inside the home.

There is no outside unit?

One of the advantages of the geothermal system is the lack of the outside unit. Many people enjoy the more pleasing landscape with no outside unit to contend with. Also, the average life expectancy is 20-25 years since the geothermal system doesn't have to deal with outside temperatures.

What about noise?

Geothermal systems are no different than anything else you buy in life. Paying a little now normally means you get less in return. A well-built and properly installed geothermal unit will give you years of quiet operation.

Can a geothermal system heat water?

Yes. The geothermal makes free hot water and can reduce your power consumption for hot water up to 60% depending on the amount of people using hot water in your home. Not only does the system make hot water, in many situations it makes "more than free" hot water. Meaning the unit actually becomes more efficient when producing hot water.

Is there a gas version of geothermal?

No. You can add a split system geothermal system to a gas furnace. This isn't normally done due to additional costs and lack of any real savings on utility (gas and power) consumption.

Can I use my existing ductwork?

Normally, yes. Ductwork should be checked to verify that there isn't any leakage and there is proper sizing. You should really consider changing the duct system on any home comfort system if there is a lot of leakage or you are up sizing your system.

How much supplemental heat will I need?

This totally depends on the heating requirements for your home. Window type, insulation, and regional climate are all major contributors.  An HVAC contractor can help you estimate if needed.  It never hurts to add supplemental electric heat strips just in case you have equipment troubles in the winter, you can use the electric for backup while you get the main unit repaired.  A wood or gas stove can serve the same purpose if you have one.

How efficient is a geothermal heat pump?

Most geothermal systems are a minimum of three times more efficient than fossil fuel systems. Geothermal simply moves heat instead of actually making it. In some instances, geothermal systems produce five units of heat to one unit of electricity.

What about the comfort levels with a geothermal system?

Geothermal systems have a good reputation for giving the highest possible comfort for the least amount of operating money. In the winter, heat normally comes out between 90 and 105 degrees throughout your home using a well-installed duct system.

How much does a geothermal system cost?

Costs vary from region to region. The main difference in cost is the loops. Most geothermal systems cost about twice as much as a high efficiency gas or air-to-air heat pump system. That kind of comparison isn't really accurate though. You should also consider: Life cycle cost. Geothermal tax rebates should also be factored in.  Having a contractor install your geothermal system can cost upwards of $20K for a 5-ton closed loop system.  Installing it all yourself and factoring in the rebates you can get one installed for half of that.

How long will normal heating/cooling systems last?

Typically, 12 years is the average. A geothermal system normally lives twice that long.

Geothermal Operating Cost?

Even the highest efficient heating/cooling system can't compare to a geothermal system. Operating cost is sometimes figured as "payback." Take the projected operational cost of the systems comparing and see how long it will take to recover your money. More comfortable people will get payback quicker due to higher energy consumption. Payback is typically 3-7 years depending on local utility rates and initial cost.

 Is hot water generated in all seasons or only in the summer when you are removing heat from the house?

Hot water is generated year round but typically only 100% of your domestic hot water will be generated 4-8 months out of the year.

What should I look for if I am willing to make this kind of investment?

Ask for referrals. Don't be reluctant to request the information where the mechanical contractor is basing the size and projected operational cost. Also, ask what the qualifications of the mechanical contractor are and how long they have been in business and installing geothermal systems. There really isn't a correct answer to the last question, just an opportunity to get a feel on the contractor.

Is there a particular brand that is better than the rest?

ClimateMaster makes great geothermal heatpumps.  They are some of the most popular sold today.  It is rumored that Bryant and Carrier geothermal heatpumps are just re-badged ClimateMaster units.  

 

DIY Geothermal Heating/Cooling

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