Manual Zr is the new ANSI-recognized standard for residential zoning. Its development was spearheaded by the Air Conditioning Contractors of America (ACCA). As the newest manual in the ACCA library, Manual Zr is the result of combined efforts of original equipment manufacturers, zoning equipment producers, and HVAC contractors.

Manual zr 1At the recent ACCA annual conference held in Las Vegas, Manual Zr was examined in two separate sessions, and manufacturers also weighed in on the importance of the new document.

Looking at Manual Zr

Dave Swett of Real World HVAC, a provider of ongoing training and education for HVAC technicians, gave a presentation titled “Overview of Zoning Manual Zr.” Swett characterized the manual as a detailed reference guide for proper design and a “must have” for any HVAC contractor’s reference library.

In his introduction to the manual, Swett listed the variables that influence zone design, including the number of zones dictated by the load characteristics of the home, simultaneous heating and cooling requirements, humidity control, temperature swings, engineered ventilation, and room air motion. He told the group that Manual Zr lays out a basic roadmap in terms of steps and sequences that have to be followed to deliver quality zoning projects.

The first part of the manual covers zoning methods, including air zoning, ductless multi-split systems, ductless single-split systems, single packaged equipment, convective and radiant heat, and central chillers and boilers. According to Swett, “Each is unique and has sets of design and operational capabilities and limitations.” He noted that Manual Zr provides guidance on each method along with where it is best used and applied.

Swett also highlighted the second part of the manual, which includes zone damper systems, system design, bypass path design, and managing excess air.

“Zoning is an exercise in discovery and going through the process using Zr takes the reader through a series of variables in the design process. You have to be prepared to change direction at any point in time during the process,” he cautioned.

Swett also called attention to several of the 17 appendices in the manual. He said they provide a “wealth of information,” including design worksheets that provide guidance on excess air and bypass airway sizing, balancing zone damper systems, and selecting supply registers and diffusers.

Contractor Perspective

Also at the conference, John Sedine, president of Engineered Heating and Cooling, Walker, Mich., and a past chairman of ACCA, led a learning lab titled, “Manual Zr from a Contractor's Perspective.”

Sedine also referred to the manual as a guidance resource for contractors. “There is some math, but it has guidance with do’s and don’ts,” he said.

Sedine shared his design process for installations done by Engineered Heating & Cooling, which includes becoming knowledgeable on everything that is available in the market; meeting with all the stakeholders and determining the wants and needs; developing a preliminary zoning strategy; and developing the primary zoning strategy, including how to handle excess air. He also mentioned other ACCA manuals that aid his process, including those for load calculations (J), duct layout (D), equipment and accessory sizing (S), proper grille and register sizing (T), and testing and balancing (B).

“I think Manual Zr will be a revelation to many contractors,” Sedine said. “In the end, it is the homeowners who will benefit.” He pointed out when equipment is sized and installed correctly, there will be fewer callbacks.

Manufacturer Perspective

Arzel Zoning, EWC Controls, and Zonefirst were all involved in the development of Manual Zr. When asked to comment on the impact of the new manual, company executives agreed it legitimizes zoning as a comfort solution in a home as opposed to just adding heating or cooling capacity.

Dick Foster, president of Zonefirst, indicated that if contractors have never done zoning, the manual “will walk them through it.” He added, “Working with a quality zoning vendor to assist in walking through Manual Zr and aiding in a couple of installations is really the best way to get started.”

Dennis Laughlin, president of Arzel Zoning Technology, noted that the manual is a good starting point. “This offers contractors permission to try zoning. They do not have to feel they are experimenting with their customers’ systems, and Manual Zr can be the guide that shows them how to professionally approach the opportunity,” he said.

“Contractors are going to benefit from Manual Zr because it takes into account all of the information that is provided from the OEMs and the zoning manufacturers, and combines that into one resource guide that is supported by ACCA,” said Mike Reilly, executive vice president of EWC Controls.

Contractors interested in offering zoning as a comfort solution can obtain a copy of Manual Zr — 2012 (Residential Zoning) from ACCA’s online bookstore at Also available from ACCA is a five DVD set titled “Understanding Manual Zr,” presented by Dave Swett, which is designed to help contractors understand Manual Zr and zoning.

Publication date: 5/14/2012