A Short Investigation

Dec. 11, 2008
Before you replace HVAC equipment, it’s a good idea to assess the condition and performance of the existing system and evaluate its capacity to accept the new equipment and new accessories. The odds of new equipment working on an old duct system are not great.

Before you replace HVAC equipment, it’s a good idea to assess the condition and performance of the existing system and evaluate its capacity to accept the new equipment and new accessories. The odds of new equipment working on an old duct system are not great.

I’ve received many requests for a process guide to walk you through the procedure of pre-assessment. The following article will provide the specific direction that you need.

The ACCA Quality Installation Standard offers a basic process intended to set a minimum bar that the industry can follow to improve the quality of HVAC system installations. One concern is that the specifications lacks a solid pre-assessment of an existing system and almost endorses the idea of simply installing new equipment on an existing duct system.

NCI research shows the average system performing at only 57% of the equipment’s rated capacity. This poor score is the result of changing out boxes without a pre-assessment procedure.

Following a well-defined pre-assessment procedure will assure adequate system diagnostics. It also gives you the opportunity to educate the homeowner so that they can make more educated decisions when it comes to their HVAC equipment.

Performing a duct renovation with testing, adjusting and balancing not only increases the revenue of the change out ticket, but also increases the performance of the system from an average of 35% to a whopping 94%. By experience we’ve learned there is no other way to achieve such high efficiency anywhere in the industry.

Imaging the disservice our industry has done to consumers over the years. A question I hear often is who will be the first manufacturer to grasp the opportunity of connecting the air distribution system and rating to their boxes? We believe this will someday become a reality as a manufacturer through trained and certified HVAC contractors certifying HVAC system performance through the National Comfort Institute’s (NCI’s) ComfortMaxx program endorsed by a manufacturer.

The Process
This pre-assessment procedure should be familiar to many of you, because it is similar to what NCI recommends during a typical replacement sale. We’ve added some minor steps in hopes that it will improve the process. Let’s take a look.

Remember, this procedure includes a substantial number of existing industry standards that you may already use.

One valuable step in this process is conducting a Comfort Survey. The primary purpose of this short interview is to discover the system defects that the consumer has become aware of by living or working in the building. Their experience may prove more valuable than some your testing instruments. Current mild weather conditions may mask defects with the system while your customer may have lived though them year after year. So ask the questions.

Continue to teach your customers as you collect the nameplate data from the equipment. Gather the model and serial numbers as well as blower size, rated static pressure and capacities. Take this information into consideration as you determine total airflow as well as room-by-room CFM, and it will provide help as you select new replacement equipment. This may be a great time to drop hints that the unit may be oversized, and to point out visible system defects.

Then draw out a floor plan of the home or building while keeping your customer engaged in the process. Record information that may be helpful when completing your ACCA manual J and D calculations once you have a signed agreement. Funny enough, we don’t recommend computerized load calculations on the same visit as diagnostic testing due to the time it takes and the distraction from the selling opportunity. But collect the necessary data and complete the necessary calculations.

Field Testing
Now bring out the tools, still inviting the customer to participate. This is a valuable learning experience for them. A knowledgeable customer assures you’ll get the job over 70% of the time. So teach.

Measure airflow from each grille, comparing estimated to required airflow. Typically 10% of the registers will have zero airflow. That’s good for you. Many rooms will have below 50%, some over 200%.

Static pressure measurement averages .82-in. on a .50-in. fan across the country, so pressure is a shocker too. Filter pressure drops are typically two to three times higher than they should be. Measure temperatures to the nearest tenth of a degree to assure accuracy and to make a brilliant impression.

Record each reading and compare results to the manufacturer’s engineering data or to industry standards. Comparison enables excellent diagnostics and pinpoints exact system defects. Carefully make recommendations for system performance improvement during the testing process. Tread lightly; it’s always best if you can teach your customer until they discover what you have to do to solve their problem.

Calculate and Diagnose
Airflow x the system’s temperature x the BTU constant = system delivered BTU. Actual CFM from supply and return duct leakage can be calculated. BTU loss or gain from the ducting can be determined and quantified. Specific blockage in the duct system as well as the resistance of existing filters and coils can be pegged. Each of these calculated values identifies system performance and pinpoints exactly where the system needs attention in addition to equipment replacement.

Good diagnostics is completed by pouring the gathered data into performance formulas with the gripper being the system’s performance rating. The CSER and HSER is the score of the system’s performance. Those that use this method claim its power to persuade the customer to add duct renovation to the change out generates closing rates higher than any other sales method available.

Prescribe Solutions
Pour the solutions into a proposal and mix it up with a fair price that delights your customer and the documented performance they’re looking for, and you have baked up a prize-winning recipe for success.

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 HVAC System Assessment Procedure, contact Doc at [email protected] or call him at 800-633-7058. Go to NCI’s website at nationalcomfortinstitute.com for free information, technical articles and downloads.