How to Prepare an Air Balance Report

June 15, 2011
Before entering the field to balance an HVAC system, assure your success by preparing your balancing report in the office, well before setting foot on the job.

Before entering the field to balance an HVAC system, assure your success by preparing your balancing report in the office, well before setting foot on the job. Good balancers agree this step reduces their balancing time in the field by 30% or more and acquaints them with the job so they are familiar with the project before they arrive onsite.

There’s no replacement for good preparation in almost anything we go after in life. Taking the time to prepare the known information contained in an air balance report while still in the office is preparation time well spent. Let’s take a look at the job data available before we walk onto a job.

Independent or Contractor Tested?

Traditional commercial balancing firms have worked independent from the mechanical contracting firm or design firm for decades. But as HVAC system performance has become the focus for today’s balancers, the independent, “match the numbers balancers” are fading into the past. Progressive building owners find increased value in firms that offer design-build and testing responsibilities by a single provider. Residential balancing has traditionally followed this model.

HVAC system performance is documentable and traceable. A clear and readable air balance report can be on-site verified with the balancer walking the job with the owner or commissioning agent in a fraction of the time it takes to balance a project.

Gather the Project Plans and Specs

Whether the job is residential or commercial, you’ll find quite a lot of data is available in the job file that can easily be poured into the balancing report while still in the office.

Pull the plans for the project and study them carefully. Verify the required information is provided to enable the system balancing. If you are balancing the system that your company has built, collect the information from the salesperson or engineering staff. If balancing as an independent, the designer or mechanical contractor is required to provide you with detailed plans and specifications.

Mark the Plans

Using highlighter pens or the highlighter tool, if plans are digital, mark the plans to identify supply registers and return grilles. I prefer blue for the supply registers and red for the return grilles. Mark equipment and exhaust systems in a different color. I chose yellow most of the time.

If not already provided on the plans, number the equipment. For example label F-1 for furnace, CU-1 for condensing unit, AH -1 for air handler. If multiple systems, number each in the order it will be tested. Label exhaust fans (EF) or heat recovery ventilators (HRV) as well.

Beginning with the supply register farthest from the equipment, number the registers in the order each will be balanced; 1, 2, 3 etc. Write the identifying numbers write on the plans (or your copy of the plans) and circle the numbers.

Repeat the numbering process for the return grilles starting with the farthest return grille. Precede the return grille numbers with an R, for return, such as R-1, R-2 and R-3.

Enter Data into the Air Balance Report

Begin entering information into the report by completing the test date, the name and location of the project, the name of the system and enter your name or initials as the balancer.

Move to the registers and grilles section, usually at the bottom of the report and complete the first few columns for each register and grille. Should you fill the page, additional registers and grilles report pages are available.

Beginning with the first supply register, enter the room name, outlet number and design CFM. Continue with a new row for each register.

Skip two rows (to allow room to add together and total the supply register airflow.)

Then enter each of the return grilles in the proper testing order providing the same information. Enter the room the register is located within, the grille number and the required airflow per the plans.

Total the supply, return, and if used, the outside airflows and enter these into the report. You’ll find an area to record these numbers in the ‘required’ column of the ‘system airflow’ section found on virtually every balancing report.

Complete any other data you have for the project or can glean from the specifications that you’re certain will remain unchanged once you get into the field.

Print a copy of the partially completed air balancing report and system plan with the grilles, registers and equipment marked on it and prepare a job file for the field.

Include the air balancing report in the job folder and all the equipment engineering data from the equipment manufacturer. You’ll need all of this information once you arrive in the field.

With the balancing report prepared with the design and project information, you’re ready to go into the field and balance. Before leaving the office, verify the systems are completely operational and ready for testing.

If you follow the steps outlined here in the office before you arrive in the field for testing, you’ll find yourself completely organized and familiar with the project in advance. This will assure effective and efficient field air balancing.

Rob “Doc” Falke serves the industry as president of National Comfort Institute an HVAC based training company with technical and business level membership organizations. If you're an HVAC contractor or technician interested in a free digital residential air balancing report that you can use in the field, contact Doc at [email protected] or call him at 800-633-7058. Go to NCI’s website at for free information, articles and downloads.