Customers pushing the “Radiant Green” button?

Combining radiant heat with alternative energy and/or ultra-high-efficiency heat sources puts “the best of both worlds” together. When homeowners want the ultimate in energy efficiency and can put more upfront money into it, they’re rewarded with uncompromised comfort, off-the-charts energy efficiency, and steroidal payback!

Leading-edge contractors are harnessing the warmth of the sun or the abundant thermal energy stored below the ground. Here’s how the Oren Atchley Company of Fort Smith, Ark., did it. We’ll also look at some of the common misconceptions about “insufficient heat” for radiant when sourced from these types of systems.

Mechanical contractor Oren Atchley Co. recently completed a very substantial residential project that spanned 38 months. For the job, they linked six geothermal heat pumps with an extensive 10-zone radiant heat system with all the bells and whistles. According to company president Mike Atchley, the project was under construction for more than three years.

The eye candy work inside this spectacular 8,000-square-foot home includes a custom-built circular stairway, cabinetry and millwork that Tom Atchley says he’s never seen the likes of in 35 years on the job, hand-milled cherry columns for the bar that were carved to resemble old, spiraled barber poles and whole-wall murals. There’s ample marble and granite, and attention to detail that few newly constructed homes receive.

The homeowners made it clear that they would entertain groups of up to 100 people and that they would like their guests to be comfortable year-round. That’s why most of the four-bedroom home’s floor space is devoted to luxuriously appointed common areas. A pool house includes an additional bedroom.

Naturally, the architect and builder were busiest in bringing the homeowner’s dream into reality. But Mike and his crew (which included the close help and counsel of his father Tom who, though now retired, still enjoys a good challenge) got their opportunity to shape and influence the home’s “footprint.”

The Oren Atchley guys are no greenhorns when it comes to sophisticated mechanical systems. They’re involved in the Radiant Panel Association and Air Conditioning Contractors of America and, on one occasion, they submitted a project for an RPA award and walked away with second-place recognition for the classification they entered; this project may be their next entry.

For every aesthetic, visually appealing surprise within the home, the Atchley guys matched it in the level of detail and care they brought to the job, though most of their work, of course, is unseen. Details include setting the extensive radiant heat system for constant circulation to ensure uncompromised comfort; using geothermal heat pumps for heating and cooling for the best in energy efficiency; and using vibration isolators on all the uni-strut clamps that connect hydronic panels to mechanical room walls to ensure that any hint of vibration wouldn’t be detected.

The two-story home sits atop an expansive basement. Most of the first floor receives in-floor radiant heat through a tubed, standard-weight concrete slab. About 12,000 lineal feet of Watts Radiant’s RadiantPEX tubing was used to distribute the 121,000 Btu of green, earth-generated heat. “Green” consideration was also given to other facets of the home, including the ample, blown-in cellulose insulation in walls and ceilings and Low E windows and doors.

Five of the 10 radiant zones are fed by two 3-ton geothermal heat pumps. The other five zones get their heat from a 3-ton, and a 2.5-ton heat pump. Flat plate heat exchangers were installed to heat the water for the radiant floors. Two additional heat pumps were set up for conventional forced air heating and cooling only via ductwork.

“The reason for having two separate systems is that the home has four mechanical rooms and the refrigerant line length [for the heat pumps] would be a problem if we placed all of the geo units on a single radiant system,” explained Tom Atchley. “Had the radiant system used a boiler, a single radiant system would not have been a problem; in fact, it would have been much easier to install.”

The radiant is set up on a continuous circulation with three-way valves directing the flow of heated water. Tom added that 50-gallon buffer tanks are installed on the north and south ends of the home. “We used electric water heaters and removed the elements so that we could have the larger diameter ports to make our connections to the tank,” he said. “Each tank has an additional 2 inches of foil-backed insulation on it to help hold the heat in the tank. This was the first constant circulation (CC) job that we installed.”

The inspiration came from John Siegenthaler’s book on the topic, trade magazine articles and postings on the Wall.

“One of our deciding factors to go with cc was that our climate is not really cold, so there’s a lot of down-time for the pumps, and tile floors can start to get some temperature swings that we would rather not have,” noted David Kuykendall, the Atchley technician in charge of the radiant portion of the job. Kuykendall designed the entire radiant manifold and mechanical rooms, as well as the electrical control panels. “Obviously, it costs more to do this, but a project of this stature wasn’t set up for cutting corners.”

According to Mike Atchley, the Tekmar stats are remote-mounted as opposed to being on the finished room walls. The control system is pretty deep. The radiant heat is the first stage of heat. If a cold snap kicks in, and the radiant can’t keep up, the system automatically switches to heat pump-generated forced air. Then, when the thermostat is satisfied on air temperature, the system automatically switches back to heating the floor. If for some reason a heat pump fails, electric back-up heat takes over, thanks to variable speed fan coils.

One of the more interesting facets of the mechanical challenge was the sunroom. This room was designed as the designated smoking room. The south wall and entire roof are all glass, so it was an advantage to isolate it from the other areas thermally and to ensure that smoke and odor would not infiltrate connecting rooms.

To accomplish this, Atchley Co. installed a separate mini-split heat pump system for the sunroom. An exhaust fan is also installed at the peak of the room for use when outdoor temperatures are mild, permitting open windows. A carbon filter clean air unit was added to scrub the air, negating smoke odor. “We’ve used these in heavy smoking areas such as pool halls, and they do an incredible job,” said Matt Holsted, the Atchley technician in charge of the hvac portion of the job. Holsted fabricated all the rectangular ductwork, and was also responsible for all the hvac, exhaust and make-up air ductwork.

The sunroom floor is made of brick pavers; Atchley Co. placed radiant tubing in the concrete slab below the pavers. “We also fabricated a radiant wall for this room that has 1/2-inch RadiantPEX mounted in aluminum plates,” added Mike Atchley.

Another interesting challenge was the master bathroom in which a large, whirlpool tub was installed. “We used a RadiantPEX with plates for the floor and the tub-surround, which is marble,” noted Tom Atchley.

The master bathroom also has two exhaust fans, one for the walk-in steam shower and one to serve the wet area and toilet area. The fans are controlled to insure that the humidity is removed before they deactivate.

“At last, it all came together perfectly, and the key measure of success was the homeowner’s satisfaction,” said Danny Johnson, project manager for the architectural firm that designed the home, Fort Smith-based Tim A. Risley and Associates. “They’re very pleased with mechanical system performance and especially pleased with the low energy costs.”

Tim Risley added, “We were also very happy with the ability of Atchley Company to make the mechanical systems, essentially, invisible. You don’t see the equipment, the heat is amazingly smooth and consistent throughout the home, and there are no aspects of it that interrupt the home’s design.

“This is the most extensive residential geo-to-radiant system we’ve had experience with. There’s a lot of new technology in this home. Our hats are off to the Atchleys. They’re early adopters, and they’ve kept pace with some of the newest, greenest and most sophisticated building systems available today. As we design homes for very discriminating clientele, we appreciate the ability to partner with firms like theirs that can deliver new and energy-efficient solutions without missing a beat.”

For more information, call 800/276-2419 or visit www.wattsradiant.com.