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Business Insights: Zoning

Originally published: 01.01.17 by HVACR Business Staff

Business Insights: Zoning

Play it Smart

Measure, monitor and maintain operating static pressure with a Smart By-Pass Damper.


Zoning in HVAC has been around for more than 50 years, and the bypass damper is the most common and effective tool available to manage airflow and static pressure in these systems. A few years ago, the California Energy Commission (CEC) conducted a study on existing homes in the state of California. Although the homes were all recently built, none of them met the 2008 California Title 24 requirements. Unfortunately, the CEC still included those homes in theirstudy.

One conclusion of the study was that bypassing air into the return duct during zonal mode was leading to the HVAC equipment losing Energy Efficiency Ratio (EER). As part of the Air-Conditioning, Heating and Refrigeration Institute’s (AHRI’s) Zoning Section Committee, EWC Controls met with the CEC to discuss the study.

“It was falsely reported that the CEC banned the use of by-pass dampers in the state of California due to the study’s findings,” says Mike Reilly, president and owner of EWC Controls.

“We pointed out to them that the homes in the study had multiple flaws in their design and operation,” Reilly says. “In fact, many of the homes had dirty filters, inadequate duct work, wrong refrigerant charges and flex duct that was improperly installed.”

These, and other factors, contributed to poor airflow and poor performance — not the return duct by-pass. EWC Controls showed the CEC that the study had many flaws in its data and its findings, due to the inadequate design and operation of the HVAC systems in the homes evaluated.

HVACR Business spoke with Reilly about the advantages of forced air zoning and the benefits of using a smart by-pass damper.

Mike Reily
President & Owner
EWC Controls


FOLLOW UP: Want to learn more? Request the final report of the Field Study of a Bypass Type Zone System’s Impact on the Energy Efficiency Ratio from EWC Controls today:

Business Insights: Zoning is brought to you by EWC Controls

How does a smart by-pass damper work?

Our Ultra-Zone Smart By-Pass Damper (SBD) captures the total static pressure of the HVAC system during a non-zoned mode, and modulates to maintain that same static pressure during any zoned mode.

As individual zone dampers open and close, the HVAC system static pressure will fluctuate. To maintain the true static pressure of the HVAC system during zoned modes, the SBD will sense the current pressure in the duct system and modulate to maintain the designed operating pressure of the HVAC system.

The SBD’s unique curved blade design provides the required pressure drop baffling within the duct system for improved By-Pass control and increased linear response by the actuator.

The SBD is the only by-pass damper that will meet and exceed all requirements of the residential zoning standard in Air Conditioning Contractors of America (ACCA) Manual Zr — the industry guide to install a zoning system properly. The Smart By-Pass Damper is the only damper that will satisfy all your needs and requirements in one design.

How were you able to reverse the CEC’s initial conclusion?

Out of the 80 homes that were studied, only eight had a zonal system using a by-pass damper that went back to the return duct. Of those eight homes, none met the requirements of ACCA Manual Zr. These homes clearly had flaws in their HVAC system which corrupted the research results.

After reviewing the CEC findings, we decided to commission a research study. We hired a local California contractor to install a zoning system per ACCA Manual Zr requirements. The home was located in Rancho Cordova, Calif. and met all state and local codes and titles.

The study concluded that using a by-pass damper in the return duct actually increases the EER of the HVAC system. Our study was purchased by AHRI and supplied to the CEC on behalf of the Zoning Section Committee. Due to this study, the CEC has changed it stance on by-pass dampers.

Why should a contractor install a zoning system rather than two HVAC units?

Some contractors install two heating and cooling units to try and satisfy the comfort needs of homeowners, but this is an expensive alternative to an Ultra-Zone system. Two units cost more to install and maintain. One unit and a damper system are far less expensive than the cost of the second furnace.

The cost of two units drastically increases when an additional air conditioner is installed. For example, in place of using two 2-ton heating-cooling systems, an Ultra-Zone system can be used with one 4-ton unit to an average savings of 30-35 percent of the overall cost.

This cost reduction comes from eliminating redundant installations. With one unit, the installation is faster and material cost is significantly less. With lower cost and more comfort features as its benefit, the Ultra-Zone system is clearly a better option than dual system installations.



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