Contractors install the ground tubing of the geothermal heating system in an excavation on the south side of a home in the Mendenhall Valley.
John Kajdan kneels in his crawl space in front of the heat pump, a component of the geothermal system he and his wife, Julie Bednarski, recently had installed in their house.
A series of ducts, part of a geothermal heating system recently installed at a house in the Mendenhall Valley, funnels air heated from the ground throughout the residence.
With the installation of a geothermal heating system air enters a residence through ducts connected to grates in the home floors. The baseboards, no longer necessary, will be removed.
Story last updated at 4/3/2013 - 3:25 pm
Julie Bednarski and John Kajdan scrawled down notes on a piece of junk mail about quotes for earthmovers, heat pumps and calculations.
That junk mail was a note mailed from a local bar and addressed to the former residents of the couples' home on Birch Lane in the Mendenhall Valley, to inform them about birthday coupons. Bednarski and Kajdan are financially savvy, but unlikely to care about whether or not a bar knows their birthday. So when they started compiling quotes and references for a geothermal heating system they were looking to install, a system that not only can be a money saver but also an environmentally friendly move, it makes sense they would use unwanted mail to collect their notes.
There are a couple of types of geothermal energy. High-grade geothermal energy is the heat formed from the pressure of the earth. Water is turned to steam, and its energy can be harnessed. Around Fairbanks for example, green houses are powered by high-grade geothermal energy.
Then there's low-grade geothermal energy, subsurface heat. Using the temperature of the ground as energy for residential or commercial heating purposes is what people are generally referring to when they talk about geothermal heating systems.
Bednarski and Kajdan had an old boiler. They had to replace it. They went to the annual Juneau Home Show in March 2012 to look for some leads on replacements. This is where they were introduced to the possibility of upgrading their boiler and baseboard heating system to geothermal.
They returned with various brochures, demeaning the intellect of the average pamphlet reader with fluffy verbiage like, "Isn't it good to know that all the energy you need to heat and cool your home is beneath your feet?," "Choosing geothermal becomes the right choice!," and photos of mullet-sporting blue-uniformed men with stitched name tags accompanied with captions like, "In our state-of-the-art production facility, highly trained workers assemble every unit with care," and "All in all, you can't buy a better engineered heat pump."
But Bednarski and Kajdan aren't fools. Kajdan's an engineer and Bednarski is a fisheries biologist. They began doing their own research, which turned out to be one of the biggest parts of the process to replace their boiler. Money was a key factor.
The state offered a rebate up to $10,000 for home energy improvements. On top of that, there is 30 percent federal tax credit on the total cost of purchasing and installing a geothermal heating system. Those two financial incentives, combined with the fact they had to replace their boiler anyhow, made the project feasible. Kajdan also estimated that their total annual savings could be around $3,000.
Add to that the environmental benefits, they would no longer need diesel fuel, there would be no carbon emissions, and as Bednarski said, a geothermal system is just more efficient, it was a clear choice.
"Heat pumps are more efficient than an electric boiler," Bednarski said. "With a heat pump you can get twice as much to 4.5 times as much heat energy. With an electric boiler you get only as much heat energy out as electricity used. So we were starting out from zero. We had to create all our own heat. That's what's so great about (a geothermal system). You're using energy that already exists."
In an interview before the work had been initiated, Kajdan presented some of his calculations.
"If we replace the boiler with a new boiler, than the break even cost, the point below which it would be cost effective to do, is $10,506," Kajdan said. "And that's basically what our out of pocket costs would be with recouping the rebate and tax credit. One of the problems we're having is that electrical energy is cheaper than burning diesel, so as people's systems age, they'll likely replace them with an electrical system, which will burden the system more. By using (a geothermal system) you reduce the electrical demand."
The main idea is that the temperature remains constant under the ground year round. The downside, Kajdan said, is that there is a specific order to installing the system, which can make the process cumbersome and lengthy.
"The learning curve is pretty tough," he said. "If you were putting in a new boiler, you'd just go to (a store)."
First, the couple had an initial energy audit, where their house's heat efficiency was graded. This gave them a base point. Their house was graded low enough that if they installed the system they could be eligible for the entire $10,000 state rebate.
Then they had to decide on whether to use water or air to heat their home.
"We went with a duct system, forced air," Kajdan said, explaining that they'd be removing their existing baseboard heating elements. "The alternative is water baseboard or, if you had a newer house, radiant. That would be an efficient way to use your water, but it takes more energy to heat up water than air."
A radiant heat system wasn't a cost effective option for them, as they'd have to retrofit the floor. They worked on insulating their crawl space well to keep as much heat in the system as possible. They also installed a new garage door, as their old boiler had been producing enough waste heat to heat the garage, and with its replacement they'd need to better insulate it.
They also had to upgrade their electrical panel to accommodate extra circuits for the geothermal system.
The geothermal system has several components. A series of plastic tubing, the required amount of which is calculated based on the house's heat load, is installed below the ground surface. They had enough room on the south side of their house for a 40-foot by 80-foot excavation.
They used a contractor to help them determine that they would need four tubes, each 1,000 feet long. The tubes enter and exit the house though a crawl space, and are attached to a pump pack there. The tubes contain a liquid comprised of anti-freeze and water that cycle continuously through the ground tubing, which were placed around 5 feet below the ground surface, just on top of the water table.
A second system of tubing contains a refrigerant. The refrigerant tubing enters and exits a compressor, or pump, housed in a refrigerator-sized box, the heat pump unit, also in the crawl space. The size of the heat pump is determined by the heat load of the house. The size of the heat pump determined the amount of ground tubing they would need.
The refrigerant tubing passes over the ground tubing entering the house.
"Then warmed refrigerant passes through the compressor," Kajdan said. "It increases in pressure, increases the temperature of the refrigerant above the air temperature in the ducts. So heat can flow from the refrigerant to the air entering the house duct system."
The warmed refrigerant then passed through a small part of the house's internal air duct system. A series of blowers moves the heated air inside the main air duct to a series of duct branches that exit into various rooms of the house.
The amount of warm air can be regulated by dampers and the diameter of the ducts. The cooler air returning from the duct system then cycles over the warmed refrigerant.
The cooler refrigerant, after exchanging its heat with the air in the duct system, passes through a valve in the heat pump box, allowing it to expand.
"On other side of valve it's allowed to expand, so it becomes very cold," Kajdan said.
The expansion process allows the refrigerant to take on heat.
After the valve, the refrigerant tubing passes over the ground tubing entering the house with the warmed antifreeze solution. The solution entering the house is about four degrees warmer than the solution exiting the house.
The system is efficient because it only uses energy already available, from the ground, and electricity to operate the heat pump, the equipment that houses the refrigerant system and compressor. The system eliminates the necessity for fuel oil or natural gas.
"It does take some electricity," Kajdan said. "But you get more heat out than the electricity that you use. The energy that you extract from the ground to heat your home is more than the energy used to run the system, pumps, fans, compressors."
In warmer climates a geothermal system can also be used to heat a water tank.
Bednarski and Kajdan recently received their first electric bill with the first day of its cycle beginning after the completion of the geothermal system. They estimated it was around 50 percent less than it had been before.
However, they have some words of wisdom.
First, a homeowner has to consider whether the cost benefits add up. If you don't need to replace an existing system, and there aren't government financial incentives, there may not be enough financial savings to install a geothermal system. Second, determining how long one plans to remain in the house is important, as the cost savings continuously increase the longer the purchaser of the system uses it. Beyond that, the couple advises spending time picking contractors.
"Have a scrupulous and meticulous contractor," Kajdan said.
For the panel upgrade an electrician was needed, and then there was the earthwork contractor and another contractor to install the heat pump and the ventilation system and duct work.
"You need a good heating and ventilation contractor to install the duct work and size it correctly for the air flow rates from the heat pump," Kajdan said. "You don't want to lose air. They have to do a good job insulating it and sealing (the ducts)."
The couple is currently in the process of resizing some of their ducts.
"The duct work wasn't the right size for some of the rooms," Kajdan said. "The velocity was too strong in some rooms, some weren't heating enough."
He pointed out that unlike a conventional heating system, you don't have zone control. The amount of heat deposited through the vents, (that replaced the baseboards), is completely controlled by the size of the ducts and the dampers.
"A change on one side of the house can affect another side," Kajdan said. "I feel like I got lucky with the contractors, but if they weren't (competent), we'd have some real problems."
In a hot water baseboard heating system, the water is heated to between 160 to 180 degrees. In a conventional oil-fired or gas furnace system, the air is heated to 120 degrees. In contrast, the air used in the geothermal system is only heated to 85 degrees. This means that the system runs more continuously; you can hear the air pumps powering up more frequently than you'd hear a baseboard system start to hum as it begins to circulate heat.
Kajdan said to be prepared for the process to take awhile.
On the positive side, the couple reported that their house is plenty warm, and not as humid as it was when they were heating with water. Also, they no longer need to rely on diesel.
"I feel like I have more energy security from spikes in oil prices," Kajdan said. "The environmental benefit is important. You have decreased carbon emissions."
Though Bednarski and Kajdan won't likely be the next cheesy smiling model couple on the front of a geothermal heat pump brochure, they may use the ones in their collection to scribble notes for their next home project.
Amanda Compton is the staff writer for Capital City Weekly. She can be reached at firstname.lastname@example.org.