Once upon a time, our ability to sell HVAC equipment was based on a marketing piece from a manufacturer, or claims we made of our exquisite service.

Once it became apparent that every contractor in the Yellow Pages (and more recently on the Internet) was making those claims, our industry started selling air conditioning and heating based on slick calculations that promised return on investment and energy savings from high efficiency equipment.

Unfortunately, most of those savings never materialized for customers because the system as a whole never had the ability to deliver the rated equipment efficiency.

Which brings us to today. Today’s buyers are more informed than ever before and make educated decisions based on their own understanding about the complete system, not just the equipment alone. That’s why we test airflow to teach our customers about the condition of their duct systems so they can make informed, intelligent, decisions based on the information we deliver about their system — not industry generalities.

When you learn to implement HVAC system performance diagnostics into your business, you’ll quickly understand that teaching is the key to selling.

Here are four simple tests that can teach customers about their system performance and persuade them to do business with you.

Test #1: Measure static pressure
Measure the total external static pressure and compare the measured pressure to the maximum rated pressure of the fan. This is a simple test that takes about five minutes.

Describe your findings to your customers in simple terms by drawing a parallel to blood pressure. For example: “Your system can handle a maximum pressure of 50 (meaning .50-in. w.c.) and its pressure is 90 (.90-in. w.c.). It’s like blood pressure that’s nearly twice what it should be. Your system can’t operate for long or perform well under these conditions.”

Continue by identifying symptoms of high static pressure that the customer might be experiencing such as discomfort, poor humidity removal, hot and cold spots, high energy expense, and so on.

Test #2 Measure system temperature changes
Knowing a system’s Delta T’s isolate the problem areas and can help you identify deficiencies in the system. Explain to customers how this will helps you solve troublesome comfort challenges they have endured for years, thinking there was no chance of relief.

Measure the change through the supply duct by subtracting the difference between the supply plenum and the farthest supply register. This shouldn’t exceed 2F to 3F. The same test can be done from the farthest return to the return plenum.

If you lose or gain 5F through the supply duct and 5F through the return duct, your total loss through the duct system is 10F. Compare a 10F loss to a 40F rise through a heat exchanger. That‘s 25% of your total BTUs that have disappeared. Or in other words, the 90% efficient furnace is now operating at less than 70%.

Test #3: Measure total system airflow
This test is by far the most persuasive. If the grille location allows, simply shoot all the supply registers with a balancing hood and add them together for total supply airflow. Compare the measured “buckets of air” to the required system airflow. Do the same with the return grilles.

The simplest way to communicate these findings to your customer may be: “You have a 5-ton system with only 3 tons of airflow.” This is not an uncommon diagnosis.

Test #4: Measure “in the field” system efficiency
Use the airflow and temperature readings to calculate the delivered efficiency of the heating or cooling system. This test results in a score or rating of the system’s performance. We find the national average system delivers less than 60% of the equipment rated BTU into the building.

This rating of the system eliminates competition with those contractors still “changing boxes. It persuades your customers to address the performance of the entire system, and to look past the efficiency rating of the equipment only.

We are confident that these simple tests, if included in encounters with your customers, will increase your ability to serve them by providing duct renovations and air balancing services. They will also help you earn increased profits and pleasure from your profession.

Rob “Doc” Falke serves the industry as president of National Comfort Institute a training company specializing in measuring, rating, improving and verifying HVAC system performance. If you're an HVAC contractor or technician interested in a free temperature diagnostics report, contact Doc at robf@ncihvac.com or call him at 800-633-7058. Go to NCI’s website at nationalcomfortinstitute.com for free information, technical articles and downloads.