AUSTIN, TX — Jim Shell put a simple question to attendees during his seminar on zoning at the Texas Chapter of the Air Conditioning Contractors of America (TACCA) 2002 Fall Conference.

“Why zoning?” he asked.

“The simple answer is people are uncomfortable at home and at work,” said Shell. “The technical answer can be found in Residential Duct Systems Manual D,” he continued, citing the 1995 version published by the Air Conditioning Contractors of America (ACCA).

Section 1-1 of Manual D states, “In order to provide a uniform sensation of comfort throughout the entire house, there should be no more than a 2 degrees F temperature difference between any two rooms.”

The sales representative for Arzel Zoning Technology Inc. (Cleveland, OH) went on to describe the advantages of selling zoning for systems in homes and businesses.

Shell said that suggesting zoning rather than complete replacements for existing systems can help differentiate contractors.

“We have been guilty of just selling boxes and not selling comfort,” he stated.

Shell talked about how the HVAC trade is letting homebuilders “dictate to us.” “They are building homes and telling us to design a system that will fit the home,” Shell said. “It is time to take the industry back — and that is by zoning.”

Shell added that home remodelers are prime candidates for a zoning system. He suggested that rather than adding a completely new system to accommodate a room addition, homeowners could add zoning.

“You’ve not only solved the problem of an addition, you’ve solved the problem, if any, of the entire existing system,” he said.

Dennis Laughlin of the Zoning Marketing Alliance (ZMA) was also in attendance. “The fourth year in a home, people start to do things — make changes,” he said. “That’s when the ‘bump’ hits.”


Shell cited an example of what it would cost to add zoning to an existing system compared to adding a second system to accommodate an addition to a home. He gave examples of a typical add-on, which included a family room, mother-in-law suite, master bedroom/bath wing, and a Florida room. Shell said that adding a new system might typically cost $4,500, while adding zoning to the existing system would cost $2,800. He also showed how these totals could be translated into “bottom line results” for HVAC contractors, citing fewer man-hours to retrofit with a zoning system.


Shell spent a lot of time emphasizing the “Arzelian Mission,” which is to get the correct bypass sizing.

“We see a lot of oversized bypass duct,” he noted. “Too big of a bypass drops static pressure and all we wind up doing is recirculating existing air. And closing off ducts increases the static pressure, too.

“It is static pressure that we want — to push air to the far reaches of the home.”

Shell quoted the “bypass theory”: “Size bypass to recirculate the minimum cfm to maintain the maximum cfm to the smallest zone.”

So why don’t more HVAC contractors offer zoning as an alternate to system replacement? Shell listed several reasons, including:

  • Zoning can be perceived as overly complex.

  • Contractors or homeowners may have experienced reliability issues in the past.

  • Contractors may anticipate costly labor or training requirements.

    “Don’t lose market share because your competitor is offering options you thought nobody wanted,” Shell concluded.

    Sidebar: Some Ideas For Improving Business

    AUSTIN, TX — It didn’t take much encouragement for Texas HVAC contractors to share some of their ideas for improving business. Well, maybe a $10 bill helped a little. Josh Kahn of Kahn Mechanical (Dallas, TX) emceed the popular event.

    Here are some of the ideas submitted by contractors during the “I’ve Got an Idea” session:

  • Conduct follow-up testing to see if new employees actually read and understand the company’s policy manual.

  • Purchase a trailer, which allows for fabricating ductwork, plenums, etc., on the jobsite.

  • Contact the local media to be put on a source list in the event that a story involving the HVAC industry comes up and quotes are needed.

  • Implement an “accident-free” program, which rewards drivers for having a clean driving record.

  • Institute a P.A.L.S. (personal, accidental, liability, and safety issues) program, in which the employer contributes money for each day with a perfect safety record, until a specified goal is reached and the money is divided among the employees.

  • Send letters to homes of employees to tell their spouse and/or family of commendable work done by the employee.

  • Distribute white T-shirts with the company logo to workers who might need to remove a dirty outer shirt while on the job.

    — by John R. Hall

    Publication date: 11/04/2002