Hillsborough resident Mark Obenshain calls himself a cheapskate.
But thats just one reason his family installed a geothermal heating and cooling system in their home.
The system, which extracts or rejects heat for the house by circulating water through pipes in the ground, takes advantage of a steady temperature of about 58 degrees 2 to 3 feet below the Earths surface.
Since switching to geothermal, the family is saving more than two-thirds the annual cost of their former high-efficiency propane system.
Its sort of like you can have your cake and eat it too for a heating and cooling system, Obershain said. If your interest is the environment, it is a renewable energy source. If youre a cheapskate, its cheap to operate. Or if you like to be outside, there is no outside condensing unit. Whatever your interest is, its a winner.
Besides saving money, his family who enjoys spending time outdoors at their house in the woods decided to install a geothermal system not only because its environmentally friendly to operate but also because it allowed them to get rid of two eyesores: their 500-gallon propane tank and the outdoor condensing unit with its annoying constant buzz.
When we figured out we could install it for about the same price as a conventional system after the tax credits we were sold, Obershain said.Three Types of
If youre thinking about installing a geothermal system, you have some choices: pond loop, horizontal loop or vertical loop systems.
The Obershains installed a vertical loop, which is the most expensive option and works by circulating about 20 gallons of water through pipes placed in vertical holes drilled in the land.
Obershain originally wanted to install a horizontal system, which costs less but requires more land to run the pipes. However, when he started laying out the pipe in their front yard, he realized the pipes would run by all their trees and possibly kill them in dry weather. The option he chose is not noticeable in their front yard, with the caps to the vertical wells flush with the ground.
Homeowners with a pond next to the house can go the cheapest route and link their pipe to the bottom of the pond, which also maintains a constant temperature like the ground. Obershain noted that the pond must be near the house, though, or a horizontal system might as well be used.Typical Cost
A system like the one used to heat and cool the Obershains home costs about $20,000 to install. Typical systems have a 50-year warranty on the pipe in the ground, and federal and state tax credits give a return of about 66 percent.
Thats pretty significant, Obershain said, noting that in the end the geothermal system cost his family about $8,000, about the cost of any other type of heating and cooling system.
The family had their system installed in fall 2010.
The timing is important for your tax credits, Obershain said. A geothermal system must be operating in the calendar year to receive the tax credit for that year. So to minimize the time between when you have to pay for the system and receive the tax credit, financially the best time is later in the calendar year.
Literature for the geothermal system states it uses up to 75 percent less energy. The Obershains system costs them $852 to operate annually, whereas their high-efficiency propane system cost $3,000. A conventional 15 SEER air-conditioning system costs about $1,700 to operate annually.Installing a System
The installation of the Obershains system took about two weeks. The planning took much longer. Obershain, who is the HVAC systems manager for UNC and a licensed contractor, designed his own geothermal system. Designing such a system, in which the water is constantly circulating, is challenging, he said, but the upfront design work is important.
You want turbulent flow through the pipes, you want it to be swirling at the edges of the pipe as it goes by, he said. You dont want the water to be laminar. It doesnt swirl against the edges of the pipe and heat transfer doesnt work as well.
In laminar flow, the water that touches the edge of pipe actually isnt moving, whereas inside has all the velocity. So it basically makes the water in there act as an insulator. It doesnt transfer as much heat. You could end up with a system that just flat doesnt work.
The Orange County Environmental Health Department requires a detailed site plan with setbacks from the street, house, septic and other features.
Sometimes it can be tricky to locate the well field, Obershain said, so a good first step is to educate yourself on these requirements and lay out ground loop options yourself.Finding Contractors
The geothermal technology is used more in the Pacific Northwest and in Virginia. Yet local contractors are getting up to speed on the technology, said Obershain, who is a licensed heating and electrical contractor but doesnt practice.
More challenging is finding a licensed well driller who is also certified by the International Ground Source Heat Pump Association IGSHPA. Orange County, which requires more inspections for geothermal systems than other counties to protect the groundwater, requires the IGSHPA certification. Well driller lists are published on the Internet, and local air-conditioning contractors may recommend drillers.
Its strange. You think of this area with the universities as being a little ahead, Obershain said, but this area is a little behind on geothermals compared to other areas in the state. Thats one of the things that fascinates me about it.
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