Tricky Installation

Having worked with Advanced Radiant Design for over 20 years, the owner didn't consider anything but radiant heat for the storage facility, according to Michael E. North, P.E., North Engineers and Design Associates, Kingston, N.Y. North was the engineer of record for the project, and his company provided design services, including site development and building schemes for the storage facility.

"The owner was familiar with the advantages of a well-done radiant system and was attracted to it due to its cleanliness, lack of clutter or items subject to damage, comfort, and economy of operation," said North.

The heating system at the Henson facility utilizes a custom-designed control panel fabricated by Advanced Radiant Design to control four zones of radiant floor heat, domestic hot water, and additional heat for the air-handling system. The radiant floor heat was installed in three different configurations, due to the different types of floor structures in the facility.

The first configuration involved a conventional radiant slab-on grade in the basement, where the client stores vintage automobiles. The distribution consisted of 8,000 feet of Wirsbo "hePEX plus" tubing, which was attached to wire mesh.

The second configuration was installed on the multiuse mezzanine and entailed tying the tubing to wire mesh on steel decking. The CAD-designed tube layout was then transferred quickly and easily to the wire mesh using spray paint, ensuring that the tubing was installed per the design.

The third configuration, which involved the main storage area for theatrical backdrops and related items, as well as an additional climate-controlled room, was a bit of a challenge.

"We put tubing in a thin slab pour that's on top of concrete planking," said Abularrage. "The pour could only be 2-1/2 inches deep, because of restrictions caused by the curbing of the steel frame. In order to accommodate this thin slab, we used a shot nailer to fix PEX rails to the planking 6 feet on center. This allowed us to get the tubing runs straight and even, since there was no wire mesh to use as a guide."

Since the PEX rails have cut-outs in them every 2 to 4 inches, it was possible to just click the tubing into the rail. While this allowed Advanced Radiant Design installers to lay out the tubing in straight lines, it wasn't 100 percent secure, especially with all the work crews that would be walking on the floor during construction. Therefore, they used one-hole straps to secure the tubing between the PEX rails, to make sure the tubing was held solidly in place.

Wirsbo MultiCore PEX/AL/PEX tubing was selected for this last portion of the installation due to its rigidity, which allows it to hold its position more securely, eliminating any chance for the tubing to float during the pour. The concrete was then poured with fiber mesh reinforcing through a crane pump.

Boilers And Balancing

All of the tubing was configured on Advanced Radiant Design's CAD system, which enabled Abularrage to ensure that all the loops would be equalized.

"This eliminated the need for brass manifolds with balancing valves, because we balanced the system out by balancing the lengths of the tubing prior to the installation," noted Abularrage. "It also allowed us to optimize the cuts from 1,000-foot coils with minimal waste."

Drawing before building is standard operating procedure for Abularrage, who stated, "We always draw our systems before they're built, including the wiring diagrams and the piping diagrams for the control panel. It all becomes part of the documentation package that we give to the customer to facilitate quick and easy servicing, should the system need it."

Heat is supplied to the system by two Buderus oil-fired boilers equipped with burner covers designed to bring combustion air directly to the burners. The boilers are controlled with a Tekmar 262 boiler control, which resets, rotates, and stages the boilers. This also provides part-load efficiency and redundancy, should one of the boilers fail.

The fuel for the system is stored in a buried 1,000-gallon, double-wall oil tank. A numericator constantly monitors the vacuum between the walls of the tank and sounds an alarm if there is a breach in either the inner or outer tank. The numericator also provides information on tank levels and fuel consumption.

A Tekmar 362 injection mixing control is connected to a Tekmar 369 zone control for distribution control. This configuration is designed to provide boiler protection and weather-responsive control, as well as indoor temperature feedback from every zone, with PID logic for optimum energy efficiency and comfort.

Bring In The Air

While heating was necessary throughout the facility, there was also a room that required air conditioning to maintain precise temperature and humidity control. This room is used to store fine art and heirlooms, so Abularrage and his team designed an air-handling system to maintain a narrow bandwidth of temperature and humidity all year round.

The room has radiant heat as well as a traditional split system air conditioner and humidifier.

"We put a heating coil in the airstream just prior to the humidifier. Whenever the humidifier is activated, a sensor in the airstream signals the coil to increase the air temperature in order to avoid condensation in the ductwork," said Abularrage.

While air conditioning was not necessary for the entire facility, a central ventilation fan was installed in the main storage room for cooling. The fan, which is controlled with a differential set point control, operates whenever the outside air is 10 degrees F cooler than the indoor air and the indoor air is above 75 degrees.

Abularrage noted that this configuration is an inexpensive way - both from an installation standpoint and from an operational standpoint - to keep that space tempered.

"In the summer, the fan will run in the evening, bringing in the cool night air and then automatically shutting off as need be," he said.

North added that all the HVAC systems are working as anticipated and everyone is happy with the final outcome.

"Not only is the owner pleased with the work done by Advanced Radiant Design, but we at North Engineers are very satisfied as well," said North.

"Due to John's knowledge and experience, I personally hired him to improve and expand the radiant system I had installed in my personal home, and I continue to recommend him on jobs in order to get the quality result we want for our projects."

The Henson storage facility definitely illustrates how the combination of radiant heat and a skillful designer can lead to amazing levels of comfort and energy efficiency.

Publication date: 08/29/2005