Alan Blum describes the drive down the quarter-mile gravel road that leads to the home he and wife Cathy are renovating as a drive back in time. “As you come upon the fieldstone homestead and see the 100-plus-year-old black walnut tree growing in the front yard, you feel as if you’ve stepped back into the Civil War era,” he said. “The ambiance is just spectacular.”

And that’s why the Blums are looking forward to completing renovations to the 3,500-square-foot home and settling in.

“We’re eager to live there permanently, but also willing to take our time and do what’s necessary to ensure we end up with a home that’s comfortable to live in, energy efficient and respectful of the environment around us,” Blum said.

And so began a top-down renovation, starting with the attic and second floor, while incorporating a ground-up geothermal heating system that relies on steady temperatures just beneath the earth’s surface to provide energy-efficient green HVAC to the home, while preserving its historic charm.

Old house, outdated heating

Located in Kiel, Wis., the 1867 homestead sits on 14 acres, along with a barn, a machine shed and a third outbuilding. When the Blums purchased it, the house boasted its original windows, 30-inch, uninsulated stone walls and drafty doors.

“All of those features are charming, but also terribly inefficient when it came to keeping the house warm,” Blum said.

Add to this a propane gas furnace that needed to be replaced, and Blum said he was in the market for a new approach to heating and cooling the home.

His first inclination was to seek advice from Dan Walsdorf, part owner, along with Sean Steffes, of Advanced Custom Geothermal in Kiel. According to records from the previous homeowner, Walsdorf had previously serviced the propane furnace. Arriving at Walsdorf’s place of business, both Blums said they were delighted to notice the company not only advertised its geothermal capabilities, but also used a geothermal system to provide heating and cooling to its facility.

“Cathy and I tend to be pretty progressive in our thinking,” Blum said. “So, as we thought about our home, we became interested in geothermal and wondered whether it would work for us. Imagine our surprise when we found out Dan did geothermal installations.”

Advanced Custom Geothermal was founded in 2007, combining two companies — Walsdorf Heating and Cooling LLC and Steffes’ company, Advanced Custom Air LLC. But Walsdorf’s introduction to geothermal came four years earlier, when he installed his first system in his father’s house.


“I had read about geothermal in general and WaterFurnace in particular, so I was eager to try the technology, and Dad’s house presented a great opportunity,” Walsdorf recalled. “Then, I decided that as long as Dad was going to do it, I should, too, because I never liked selling something I didn’t believe in or hadn’t tried first.”

Today, the WaterFurnace dealer says at least 75 percent of his HVAC construction business is the installation of green HVAC geothermal systems. But before he recommended geothermal to the Blums, he first suggested they employ another local firm to conduct an energy audit of the house, which would show the home’s heat loss and generate suggestions for improving its energy efficiency.

“We would sooner not put in geothermal and lose a sale if homeowners would agree to the audit and make their home tighter,” Walsdorf said. “You have to do it systematically, and that means making a home more energy-responsible with insulation, better windows, etc., before considering the heating system. The more upgrades a homeowner makes, the greater impact it will have on the heating and cooling system we design for them, often resulting in a smaller system.”

The Blums followed Walsdorf’s advice, began work on insulating the house and made plans to replace its 37 windows. Then, they went back to Walsdorf to explore the possibility of installing a geothermal system.

A geothermal system takes advantage of free solar energy stored just below the surface of the earth. Using a series of pipes (an earth loop) buried in the ground and a geothermal or ground-source heat pump, the geothermal heating and cooling system extracts heat from the earth and carries it to a home in the winter. An indoor unit compresses the heat to a higher temperature and distributes it throughout the home.  In the summer, the process reverses and the system extracts heat from the home and rejects it to the earth. In both cases, the geothermal system delivers consistent temperatures and efficiencies that exceed those of conventional HVAC market systems, offering homeowners savings as high as 70 percent for heating, cooling and hot water.

Better air

In addition to consistent temperatures, a geothermal system can ensure good indoor air quality. That’s because the system does not require combustion and produces none of the products associated with combustion, including carbon monoxide, which can be dangerous if not vented properly. And, the average geothermal system lifespan exceeds 24 years — compared with 15 years for a more traditional heating and cooling system.

All of these benefits appealed to the Blums, but they needed Walsdorf to confirm that their home was a good candidate for a geothermal system. Based on the results of the energy audit and what he already knew about the property, Walsdorf said he was confident that a geothermal system would provide the efficiency, comfort and sustainability the Blums sought. In fact, he predicted that the heating and cooling expenses for the house would shrink from the current level of $5,390 per year to just $1,963 per year by installing a geothermal system designed around the WaterFurnace’s 7 Series variable-capacity geothermal heat pump.

“I realize that some of those savings can be attributed to new windows, insulation and other upgrades to the house,” Walsdorf said. “However, I’d say at least $2,500, if not more, is a direct result of the geothermal system.”

The geothermal system at the Blum house uses eight 300-foot trenches, with 600 feet of pipe in each trench.

“That may sound like a lot, but if we had used a single slinky loop in a smaller land area, we would most likely have needed 9,600 feet of pipe, or almost twice the amount of pipe we actually used,” Walsdorf said.  “In this case we had plenty of land to work with, and so we were not confined to a single horizontal loop or a drilled vertical loop, which can be much more costly.”

Although an abundance of property worked to the advantage of those installing the loop, the age of the home did not.

Ductwork fabrication challenges

According to Walsdorf, “The ductwork was 100 percent inadequate. In addition, the homeowner wanted five zones in the house, which meant we needed five separate trunks of ductwork, which isn’t easy to do in an existing home, especially one as old as this one. The system we designed was carefully crafted to ensure the delivery of comfortable, filtered air throughout the home and included special details, like double-radius elbows, and tape sealed and caulked joints for maximum transfer efficiency.”

Selecting the right piece of WaterFurnace equipment was easy for Walsdorf, who said that the 7 Series unit was a perfect choice, providing the design flexibility he needed to meet the Blums’ requirements.

“The Blums wanted five zones, and prior to the introduction of the Series 7, there was no geothermal unit capable of meeting that requirement,” he said. “Up until now, the most I could provide with a two-stage unit was four zones, and the smallest of those zones had to handle 40 percent of the total system output.

“But, the 7 Series variable-speed unit allows us to have more zones than conventional two-stage equipment — up to six — and allows us to design smaller zones,” Walsdorf said. “So, now we can make a 150- or 200-square-foot bedroom its own zone without worrying about too much air entering the space. The variable-speed feature on the unit allows the unit to scale output to exactly the level needed rather than the high or low speeds found in normal systems. The unit can ramp down to 20 percent of normal operation for ultra-efficient conditioning or up to 130 percent output using SuperBoost, for periods when extra heating or cooling is needed.”


WaterFurance says that the 7 Series is the only unit to surpass both a 41 energy-efficiency ratio and a 5.3 coefficient of performance. This represents efficiencies twice that of traditional air conditioners or heat pumps and 30 percent greater than current geothermal units.

In addition to energy savings, the Blums were able to take advantage of a federal tax credit that amounts to 30 percent of the installed price of the system.

“I don’t like to sell geothermal on the basis of tax credits,” Walsdorf said. “We were growing our geothermal business even before the tax credits came along. However, they definitely help, making a geothermal system much closer in cost to a high-efficiency conventional system. Add in the energy savings you realize with a geothermal system and the decision to go geothermal becomes a no-brainer for many people.”

It is a decision the Blums say they are happy they made.

“The master bedroom is always within one degree of the set point, despite the fact that there are four drafty windows in the master, three of which are single-paned without any storm windows or insulation around the jams,” Blum said. “I’d say that speaks to the efficiency and reliability of the system. In addition, we don’t have to listen to a noisy unit on the outside or see it, which means the geothermal system will help preserve the look of the old home. And it’s green, which is another benefit that is important to Cathy and me. We’re relying on the earth to heat and cool our home rather than other fossil fuels.”

According to the Blums, the geothermal system is contributing to a beautiful home that is as efficient as it is charming. Just as importantly, it has introduced them to a contractor who they now consider a friend.

“After talking with Dan, I knew he was the guy I wanted to work with, and I’ve never looked back. If there was anything I needed, he came over immediately and attended to it,” Alan Blum said. “He’s very knowledgeable and obviously loves what he’s doing. I really can’t say enough about his company and their dedication and commitment to what they do and the customers they serve.

“Sometimes you have to take a shot in life. This was a big one for us. But we did it, and now we have a great house and a good friend in Dan.”

 This article and its images were supplied by WaterFurnace International.