Once your static pressure measurements are complete, add fan airflow to your skill set. You have two options depending on the test instruments you own.

The first and easiest option is to estimate fan airflow with a fan table. You can get this reading quickly with the operating fan speed and manufacturer’s fan table for the air-moving equipment.

The second and most accurate option is a direct fan airflow measurement using the Digital TrueFlow Grid.

At this point in testing, the customer has a decision to make. If they want to proceed with Duct Optimization, you’ll need more information to further diagnose the duct system like delivered airflow and temperatures into the living space.

Do not perform this type of assessment for free or as part of a sales call. The customer should pay for this service and be fully involved in the testing process.

If they decide to go with further testing, you’ll need to measure delivered airflow into and out of each room. You’ll need an air-balancing hood and anemometer for these duct measurements. Make sure you know how to use these test instruments and understand the factors that influence them.

It’s also a good idea to compare supply register and return grille temperatures to those measured at the equipment. This diagnostic test helps identify missing or inadequate duct insulation.

Use Best Practices for Design and Verification

Before you optimize any duct system, make sure the equipment is sized correctly. Unless you enjoy owning nightmare jobs, I recommend you avoid Duct Optimization on oversized equipment. If the equipment is oversized (and it usually is) this is a great time to recommend upgrading to the proper size.

This is also a great time to make sure you understand and can apply the principles found in ACCA Manual D. It’s the HVAC industry standard for duct design.

Start in the appendix for some great information to understand important duct system principles to ensure you meet equipment design specifications.

When sizing an existing duct system, few contractors have the free time they need to reverse engineer an existing installation.

Experience shows that field installation conditions rarely result in a well-performing duct system. If the duct system design was bad from the beginning, it needs an upgrade.

Test the system once work is complete to verify that your design methods work. That’s where the rubber meets the road. It doesn’t matter how good your design skills are, unless you verify with measurements, you’re guessing.

Focus on Installation Details

It’s easy to forget that your installers control airflow. They’re the ones in tough conditions who ultimately determine how well a duct system performs. Make sure they understand why duct sizing, fitting construction, and proper sealing are so important.

Click Below for the Next Page: