Since the mid 1980’s most contractors have been selling air conditioning and heating using methods like slick calculations that promised return on investment and energy savings. Times have changed and so have our customers. Today’s buyers are better equipped to make informed decisions based on their own understanding. Many do their own research – thanks in large part to the internet. Our ability to persuade can no longer be based on a marketing piece from a manufacturer or casual claims of exceptional service. After all, that’s what every other contractor in the yellow pages offers.

Today we can test system performance to teach our customers about the condition of their entire HVAC system. By providing the facts, we enable them to make informed intelligent decisions. When you implement diagnostics you’ll quickly learn that teaching is the key to selling.

Four Easy Tests

I’d like to share with you four simple, yet powerful tests that can teach customers about their system’s performance and persuade them to do business with you. If executed properly, these testing and teaching methods allow you to dismiss your competition.

Prior to performing some or all of these tests, be sure to interview your customer, asking pointed questions about comfort, air quality, energy usage and other comfort system-related concerns. This will help set the stage for explaining your findings through the diagnostic testing. It will also help you determine which of these tests to conduct on your sales call.

1. Static Pressure. Take total external static pressure readings. Compare the measured pressure to the maximum rated pressure of the fan. 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″ w.c.) and you current pressure is 90 (.90″ w.c.). It’s like blood pressure that is nearly twice what it should be. The system can’t operate for long or perform well under these conditions.” Continue by identifying the symptoms of high static pressure that they might be experiencing such as discomfort, poor humidity removal, hot and cold spots, high energy expense, etc. You can download the Static Pressure Procedure from the Technical Downloads page on NCT’s website.

2. Total Airflow. This is the most basic test. If the grille location allows, simply shoot all the supply registers with the hood and add them together for total supply airflow. Compare the measured “buckets of air” to the required 400 CFM per ton or to room-by-room CFM estimates. Do the same with the return grilles. The simplest way to communicate your findings to your customer may be: “You have a 5-ton system with only 2 tons of airflow.” The HVAC System Report, located in your NCI Air Balancing Forms and Procedures is a perfect form for documenting your test results.

3. Temperature Changes through the system. System Delta T’s isolate the problem areas and can identify deficiencies in the system. This helps your customers identify troublesome symptoms they have endured for years without any 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 2-3 degrees. The same test can be done from the farthest return to the return plenum. If you lose 5 degrees through the supply duct and 5 degrees through the return duct, your total loss through the duct system is 10 degrees. Compare a 10-degree loss to a 40-degree rise through a heat exchanger. That equals a loss of 25% of your total BTU’s. This test also identifies problems with ducts inside the building envelope – especially in soffit area or where the ducts pass through rooms with varying heat loads.

4. Field measured system efficiency. Use the airflow and temperature numbers that you have gathered above to calculate delivered sensible BTU’s. Multiply the supply airflow times the temperature change from the average supply register to the average return grille. Then multiple by the sensible heat constant of 1.08 to find System delivered BTU’s. Divide delivered BTU’s by the manufacturers rated BTU’s to find the percentage of BTU’s delivered. Multiply the equipment rated efficiency by that percentage to find the field measured system efficiency. We provide a step-by-step Effective Efficiency Procedure in the NCT Technical Downloads to guide you through the process and document results.

We encourage you to continue to implement diagnostic testing and teaching in your daily service and sales activities. We’re confident this will increase your ability to serve your customers by providing duct renovations and air balancing services and earn increased profits and satisfaction from your profession.