ACHRNEWS

Mountain Hydronics With a Twist of Geo

January 23, 2012
mountaintop home
“Take notice of the giant cottonwood trees lining the streets of town,” said D’Aron Johnson, owner of Ambrose Heating and Cooling, based in Hamilton, Mont. “Those were planted by copper king Marcus Daly when he founded the town.” Johnson added that, given the fashion of the mid-1800s, Daly didn’t want his wife getting a tan while riding down the street in an open carriage.

Hamilton’s history is multifaceted, from silver and copper mining around the turn of the century, to becoming a hub for the medical industry a century later. Both Rocky Mountain Laboratories and GlaxoSmithKline, two microbiological research companies, set up camp there in 2005.

In 2000, Hamilton and the surrounding Bitterroot Valley were dealt a heavy blow when huge forest fires ignited in the Sapphire mountain range.

“That year brought the fires, but it also brought the beginning of my business,” said Johnson. After years of working as a manager for another HVAC firm, and spending time as a manufacturer’s rep, Johnson and his wife, Angela, decided it was time that they set out on their own.

Today, Ambrose Heating and Cooling employs seven technicians, all of whom routinely travel throughout the western part of the state. The company’s specialty is providing geothermal retrofits, but a variety of new construction and service work keep the whole team busy.

Sounds of Ponderosa

A few miles out of town, you can almost hear the “Bonanza” theme song as you pull up the switchbacked driveway at the end of a gravel road. At the top sits an over 6,000-square-foot custom log home where Ambrose completed a geothermal retrofit this summer. With over 300 acres, the ranch really looks the part. Its scenic overlook offers 20-mile views and eagles soaring above.

“You can’t even tell we were here,” said Johnson, looking at the green lawn where his crew installed 10,000 lineal feet of 3/4-inch geothermal exchange pipe only months before. Surprisingly, the valleys within the Rocky Mountains are generally horizontal-loop-friendly. Unlike East Coast installations, only 10 percent of the exchange fields Ambrose installs call for a drill rig.

“Having a good excavator, and knowing how to fuse a ground loop keeps our cost down,” said Johnson. “Typically, using a drill rig will triple the cost of an exchange field installation.”

“With low installation costs, customers never regret oversizing ground loops a little,” added Johnson. “The heat load calculation on this home called for 135,000 Btus at ASHRAE design conditions. We’ve got plenty of exchange.” While winters rarely reach the severity seen in northern Canada and Alaska, Mother Nature can be cruel in Montana. To stay on the safe side, Ambrose technicians fill the pipe with a 25 percent methanol mixture.

The mechanical space for the ranch home is located on one side of the garage. Walls of the entry area display an assembly of circulators and PEX tubing, installed with the original boiler in ’94. The home was (and still is) heated by 13 in-slab zones, and an 80-gallon indirect tank drew heat from a 200 MBtuh, LP-fired boiler before Ambrose was asked to perform an energy-improving retrofit.

Rounding the corner in the garage, HVAC technology skips a decade. The rancher’s desire to trim heating bills led Ambrose to install a 10-ton ClimateMaster TMW water-to-water heat pump. The recent changes are expected to deliver an 80 percent reduction in heating costs.

“We use a lot of these systems,” said Johnson. “And we haven’t had any trouble with them in the past 10 years.” The large unit is piped to a storage tank that feeds the radiant manifold, and the nearby boiler can supply supplemental heat in the event of a bitter cold spell.

A 50-gallon Bradford White electric water heater is piped in series with the existing indirect tank, ready to provide heat if the domestic water temperature needs a boost. The homeowners have learned that a house full of guests can deplete even the big tank.

“We piped everything with inch-and-a-half Aquatherm,” said Johnson. “The product isn’t new, but it’s fairly new to the U.S., and is very easy to use.” With fuse-welded fittings, the green polypropylene pipe looks clean and unique in a mechanical space. “What we especially like is that their flexible pipe can be direct-buried to run from the geo-exchange field into the building without the need for a transition.”

Homeowner Specified

Several miles from the ranch, on a hillside now brimming with young timber after a wildfire 20 years ago, is a modest, two-story home with a porch on two sides.

“He’s not your everyday client,” said Johnson. The 75-year-old homeowner is a retired Bell engineer. He contacted Ambrose last year for a geothermal retrofit at his 3,200-square-foot home just outside Hamilton. “He said he wanted to heat his home and 18,000-gallon pool with a geo system,” continued Johnson. “He designed the system himself, from the ground loop to the heat exchanger for the pool, and the concept all checked out.”

The first-floor mechanical room is tight. The existing 199-MBtuh high-efficiency boiler, 5-ton ClimateMaster TMW water-to-water heat pump, water softener, and bank of circulators are all found inside. System flow is achieved using Taco 007 circulators and zone valves. The boiler feed is guarded by a Watts backflow prevention valve.

In a crawl space under the mechanical room, there was just enough space for two 50-gallon Bradford White Lowboy tanks. The two tanks, which are only 34 inches tall, made use of the low space when there was no more real estate to be had in the mechanical room. One of the electric tanks provides storage, while the other tempers water for the existing indirect tank, if necessary. A Taco domestic hot-water recirculation system was installed at the owner’s bidding.

Now, while enjoying a view of Hamilton, the owner can enjoy a hot swim on a cool spring morning, steam rising gently into the crisp mountain air. A plate-and-frame heat exchanger is located in the pool shed. An insulated 1-inch PEX line running under the lawn connects the heat exchanger to the crawlspace hot water storage tank.

“The beauty of the pool is, it’ll only be used from Memorial Day to Labor Day, when there’s no heating requirement for the house,” said Johnson. “The owner is getting double duty from his ClimateMaster unit, so he’s heating his pool and his house for 20 cents on the dollar, compared to what he’d pay for LP gas.”

Almost Finished, Radiant-Ready

On the other side of Hamilton, and situated on top of its own hill with magnificent views of three mountain ranges, is a home containing Johnson’s most recent work.

Rough-cut siding and a rusty metal roof give the 5,000-square-foot house the appearance of a stately barn. On the inside, reclaimed barn timbers and floorboards add to its charm.

Although the house is beautiful and completely livable, the areas above the three-car garage and large basement are yet to be completed. “For the client, there are other things to spend money on at the moment,” said Brandon Roberson, Ambrose technician. One thing that wasn’t open for compromise was the quality of the HVAC equipment.

“The owner is a single mother with two teenagers,” said Johnson. “Halfway through the project, the GC [general contractor] moved out of the area abruptly, and left her hanging. From there, she took over, and did a pretty good job of it. Needless to say though, it brought up some challenges for her.”

The home currently has two geothermal heat pumps, and a third is slated to go in. A 5-ton ClimateMaster Tranquility 27 water-to-air unit serves the voluminous basement and main floor. For the second floor, a 4-ton Tranquility 27 unit was used. Both units are equipped with a desuperheater, which preheat water supply for two 80-gallon electric Bradford White water heaters.

With a suggestion from Johnson, 3/8-inch PEX went in just before the slab was poured. Sealed and sleeved loop ends protrude from the concrete against a bare wall in the mechanical room, ready to be connected to a ClimateMaster TMW heat pump when the owner gives the go-ahead.

“We use round duct when we have the space,” said Johnson. “It keeps the velocity noise down.” Beyond detail in designing the system, an Ambrose installation is sure to have all the finishing touches. Mastic is used on all duct joints so efficiency isn’t decreased; a problem they avoid because tape eventually dries out. All heat pumps are mounted on top of 2-inch rigid foam insulation, to eliminate vibration and noise.

Family Man, Again

Although Johnson couldn’t be happier in any other industry, his true contentment lies at home. His four children, Michael, Kristina (recently married), Jade, and Josiah, take full advantage of their Rocky Mountain surroundings. Hardly a weekend goes by between April and October when the big camper and truck aren’t loaded up and hauled into the vast expanses of western Montana wilderness.

“We camp as a family, and I often end up cooking for 20 or more.” Johnson cooks eggs by the dozen in a 36-inch cast iron skillet; coffee is brewed by the gallon.

“Now that our first two children are grown, we decided to start over and make a difference for other children,” said Johnson. Through a foster program, they’ve come to know two children from a broken home. The brother and sister, ages 10 and 11, are now permanent members of the Johnson clan.

“Sure, we’ve had some challenges,” said Angela, “but they’re now our second pair of children, never again to be passed around between foster homes.”

Publication date: 01/23/2012