Difficult Designs: Systems That Make TAB a Challenge

Some HVAC systems look simple on paper

In the field, they tell a very different story.

Shared outside air ductwork. Fresh air ducted to a dozen small units. Grille face dampers doing the job of a real balancing device. None of that shows up as a problem in the design documents or the sequence of operation - it shows up on site, when someone's trying to measure airflow that was never set up to be measured.

CxPlanner is proud to sponsor this AABC webinar - and the topic hits close to home for anyone who has tried to balance a system that was never designed with TAB in mind.

What the course covers

This course examines the system configurations that most often create difficulties for TAB professionals: shared outside air ductwork, fresh air ducted to multiple small units, grille face dampers used as balancing devices, enclosed rooftop exhaust units, complex sequences of operation with moving targets, and simplified hydronic pump arrangements.

Through real-world field examples, David E. Gilbert will explore how these design approaches affect airflow measurement, system stability, and the ability to properly test and balance HVAC systems - plus the practical design considerations that reduce TAB challenges and support reliable performance over the life of the building.

By the end of the session, you'll be able to:

• Identify HVAC system design configurations that commonly create challenges during Testing, Adjusting, and Balancing (TAB)
• Describe how outside air distribution methods and duct configurations affect airflow measurement and TAB procedures
• Explain how control sequences, balancing devices, and equipment configurations influence system performance during TAB
• Recognize design considerations that help reduce TAB difficulties and support accurate system testing and adjustment

Why this topic matters

TAB is where design decisions become real problems. A duct layout that looked fine in the model creates measurement challenges on site. A system that passed design review turns into hours of troubleshooting during commissioning.

That gap - between what's on paper and what you find in the field - is exactly where commissioning teams spend most of their time. Documenting deviations, tracking re-tests, managing the back-and-forth with design teams.

CxPlanner is built for that gap. When a TAB result doesn't match the design, you need a clear record - what was tested, when, by whom, and what happened next. That's not paperwork. That's the commissioning process working the way it should.

About the webinar

Speaker David E. Gilbert, TBE of Fluid Dynamics, Inc. brings hands-on TAB expertise to a topic that rewards practical experience over textbook knowledge.

The webinar is hosted by the Associated Air Balance Council (AABC) - a non-profit dedicated to educating and improving TAB and commissioning professionals.

Register here →