Branch or Trunk

But, continued Laughlin, “Probably the biggest difference is that we promote the principle of branch dampering vs. trunk dampering.”

Most homes have some major trunks that come off the plenum of the furnace that will then split into branches that service the different rooms of the home.

“Traditionally, zoning has been done by utilizing two or three trunk dampers, keeping sections of the home at approximately the same temperature,” said Laughlin. For example, there might be an upstairs trunk and a downstairs trunk.

But homes often need more flexibility than trunk dampering allows, asserted Laughlin. A temperature that’s suitable for the master bedroom may not be suitable for the baby’s bedroom. Branch dampers, on the other hand, allow individual rooms to be controlled.

A major drawback with branch dampering, conceded Laughlin, is cost. It requires more dampers and adds more wiring, boosting the price. Arzel’s low-pressure air-actuated dampers, though, are only about half the cost of electromechanical dampers, he said, to make branch dampering cost efficient.

Pump Up the Dampers

The air-actuated dampers are powered by an industrial mini-pump mounted in the system’s panel box. The pump creates both vacuum and pressure, because the dampers close on pressure and open on vacuum.

Since the system uses low-pressure air, PVC tubing, rather than wires, is connected to the dampers. The tubing is “simple to work with,” Laughlin said, and enables installation to be accomplished “much quicker.” With a low-pressure air system, there’s no problem with condensation. It’s also a safe system, he added, operating at 1 to 3 lbs pressure.

Another difference with the Arzel approach is that gasketing is used to seal around the dampers, providing a tighter fit and less air leakage than with conventional zoning systems, he maintained. Also, installing electromechanical dampers in a retrofit application can require renovation of the ductwork. Laughlin said his company’s damper is installed by cutting an access hole in the side of the duct using a template, sliding in the damper, securing it with four sheet metal screws, then attaching the air line.

“Most of our contractors tell us they put in a damper in 10 minutes or less,” he asserted. This is compared to up to an hour with an electromechanical damper, he said.

The air-actuated dampers can be used with flex duct and duct board. And the company can do custom sizing as needed.

The system is designed to be “retrofit friendly,” noted Laughlin, but it also can be used for new installations.

For those applications where a contractor doesn’t have access to the ductwork, the company offers its RegiDamper™. This product slides into the boot at the register, providing much quicker and easier installation than having to tear out and patch drywall, he remarked.

With all of its advantages, Laughlin thinks that zoning’s day is coming and it will be here soon.

“I really believe that the time is rapidly approaching when you see zoning as a mainstay of every designed hvac system,” he said.

For more information, contact Laughlin at 800-611-8312 or 216-831-6068; dennis@arzelzoning.com (e-mail).

Sidebar: Obituary

ESCONDIDO, CA — Mike Rogers, a longtime vendor and trade show magician, died on June 11, 2001. According to McQuay International, Minneapolis, MN, he had performed at AAF and McQuay trade show displays at hvac industry events.

According to the company, for the past 27 years, Rogers provided close-up magic and slight-of-hand acts for trade show visitors during the American Association of School Administrators and National School Boards Association events. The family has requested that donations be sent in his name to Elizabeth Hospice, 150 W. Crest St., Escondido, CA 92025.

Publication date: 07/30/2001