Sigman Heating and Air Conditioning/Sigman Indoor Climate Solutions LLC is no stranger to the Quality Home Comfort Awards. Perennial winners, Sigman is known for its ability to land some of the largest and most interesting residential projects in St. Louis area — or anywhere in the U.S., for that matter.

Still, there must have been some dropped jaws even at such an experienced company when Joel Sigman, president of the company's indoor climate solutions division, brought the team together to begin planning the comfort system for a newly constructed home with 41,000 sq.ft. of conditioned space. No matter how many large and complicated projects a company has done, a number like that must cause the team's collective hearts to beat just a little bit faster.

"To say the least, this is the most space that our company has ever conditioned for a residential home," says Joel Sigman. "This project involved every aspect of a heating and cooling system on a large scale. Not many things were missed in this home. Indoor air quality was satisfied with fresh air ventilation, HEPA filters, and humidity control, and efficiency was taken care of with geothermal, radiant heat, high efficiency boilers, and good design."

The final design for the forced air system called for 16 geothermal systems totaling 68 tons, with an additional four geothermal systems totaling 40 tons for the radiant system.

The geothermal systems are driven by a large loop field. The field is broken down into four pods of 16-tons. There are 12 wells at 200-ft. for each pod. The primary loop manifold has 14 crossovers and 4-in. copper pipe. The manifold for the primary loop had to be built on-site. It covers the entire basement sidewall (14-ft high) and hangs from the ceiling. The return and supply lines are tied together in a first in/last out configuration.

"The weight of all the copper made mounting and securing the manifold difficult, because there were minimal places to install brackets," Sigman says. "The weight was such a concern that as the manifold traveled across the ceiling the carpenters installed additional floor joists that sat from beam to beam, but were shorter than the main floor joist, so that the main joist would not carry any of the weight."

Each crossover is piped to a flow controller. The manifold is built with multiple ball valves so that all the piping can be easily flushed. The pumps are set up in parallel and series to satisfy the 192 gpm flow. The 4-in. pipe splits for each of the sets of pumps, and features check valves to prevent back flow. This pump design allows for proper flows, quiet and efficient pumps, and means that the system will not shut down upon a pump failure.

"The house was to have poured concrete on the floors, so we offered the homeowner the option of radiant heat," Sigman says. "It made sense since many of the ceilings on the main floor are 14 ft. to more than 20 ft. high. The radiant heat system has 18 zones and covers over 30,000 sq.ft of floor. The tubing for the home's sunken basement, basement, and four-car garage (not to be confused with the homes other, five-car garage) is set on 12-in. centers. The indoor pool, main floor, and second floor are set on 6-in. centers. There are 134 circuits, 24 manifolds, and more than 50,000 ft. (that's 9.5 miles) of ½-in. oxygen barrier PEX tubing. The system uses four 10-ton water-to-water units to create enough hot water to heat all the spaces that have radiant heat, and the indoor pool.

Challenges arose in making sure the forced air system kept up with all the changes that took place as construction progressed. For example, the grand salon’s outside wall was pushed back about seven feet and a third floor observatory added — and then topped with a fourth story lookout. These changes created some "redesign-on-the-fly" challenges for the Sigman team. The second floor and two of the bedrooms on the main floor were originally going to be conditioned using two 5-ton systems. With the addition of the observatory the systems were split, making three systems for the second floor, a separate air handler for the main floor bedrooms, and five zones.

The room below the main floor bedrooms the art studio with an exposed ceiling and spiral duct, which meant no duct could run below the bedroom floors. The observatory was tricky because there was very limited space for the supplies and the duct. The solution was a Unico high velocity duct system. "This allowed us to set the air handler in the limited space provided and get the supply outlets up to the fourth floor lookout, which is accessed from a spiral staircase that goes up from the observatory floor," Sigman says.