During the 4th Annual HVACR Training Symposium, Jim Bergmann and Chris Hughes teamed up to give their humorously titled session, “HVAC Commissioning on Steroids Without the Pimples.” They talked quite a bit about commissioning tools like measureQuick and Trueflow and showed how someone could use them to test for return duct leakage.

Leaking ducts, dirty blowers, and duct restrictions are common problems that cause poor airflow, but it's difficult to explain them to the customer in terms that they can understand. Moreover, those issues are some of the biggest enemies of performance and efficiency, more often than equipment age and poor maintenance. Even though airflow may seem good on the surface, low superheat, low suction pressure, and low head pressure indicate possible airflow problems.

Return duct leakage can significantly reduce system capacity and efficiency. When we have leaky ductwork, we often have higher latent BTU gains, which reduces the sensible capacity (and the thermostat measures sensible heat). Return air leakage often comes from hot, humid unconditioned attics as opposed to unconditioned outdoor air, which makes up a good portion of supply air leakage.

You can estimate the impact of return duct leakage using the Mixed Air Formula, which requires two mixed air probes and measureQuick. You'll need to know the duct leakage drybulb temperature and return air drybulb temperature, and you'll get the mixed air drybulb temperature. Even though the mixed air drybulb temperature may only differ from the return air temperature by only a few degrees, it has a significant impact on the evaporator coil by increasing the dew point, which reduces the efficiency and costs the homeowner more money. measureQuick will display the data picked up by your test instruments and estimate the leakage and capacity loss with its Duct Leakage Screening feature. By watching their full session, you can learn how to do that test and add some more gamechanging commissioning strategies to your toolbox.

TrueFlow integrates with measureQuick, and the apps alert the users when the measured airflow (TrueFlow) differs from the estimate (measureQuick), which indicates likely leakage and lets the HVAC contractor know that it's time to investigate the problem more thoroughly. The issue could also lie in improper probe placement, but most discrepancies occur due to duct leakage. When the two apps agree, then the user can be confident in the data and capacity.

Equipment capacity differs from delivered capacity in that equipment capacity is produced at the equipment and doesn't necessarily make it to the conditioned space. Delivered capacity accounts for BTU gains and losses that happen in the ductwork. Proper commissioning and catching the causes of reduced delivered capacity bring a lot of value to the customer and reduce the likelihood of callbacks.

measureQuick also has a vitals score based on measurements. The app shows the range of performance and identifies how the system measures up on those performance criteria. measureQuick also now reviews the performance of subsystems. It enables users to learn more about corrective actions, take photos to document a system, and use a geolocation feature to assist with documentation.

When technicians purchase tools and software to help with advanced diagnostics, they have the right to price their services accordingly. We can be confident that our more thorough results justify a higher price tag, which you can set based on your gross revenue target. You can figure out your gross revenue target by accounting for your sales, job cost, gross profit, overhead, and net income. We can also communicate our results to customers with simple visuals that customers can understand, such as those in TrueFlow and measureQuick's reports.

Jim and Chris also covered:
Impacts of leaky return and supply ductwork
How to sell the value of the work you do with confidence
Using commissioning to catch issues
Workflow and Illustration of Workflow and Diagnostic Test Methods ( ANSI / RESNET / ACCA / ICC 3102020 )
Establishing a commissioning process at your company

Steve Rodgers and Bill Graber class on Supply Duct Leakage from 3rd Annual HVACR Training Symposium:    • Dealing with a Problem Home, A ''Bask...  

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