Static Pressure is like Blood Pressure - Short #258 · HVAC School - For Techs, By Techs summary

Key takeaways

Static pressure is essential for HVAC efficiency, much like blood pressure is for cardiovascular health.
Regular measurement of total external static pressure (TESP) should be routine during HVAC maintenance.
Low static pressure isn't always good; it may indicate airflow issues just as high blood pressure can indicate health problems.

Summary

Understanding Static Pressure

In this episode, Bryan explains the concept of static pressure in HVAC systems and compares it to blood pressure. Just as blood pressure indicates the health of the circulatory system, static pressure shows the efficiency of airflow in HVAC systems. Proper measurement and understanding of total external static pressure (TESP) are critical during maintenance and service.

Measuring Static Pressure

Bryan discusses the importance of regularly measuring static pressure and the specific testing ports needed for air handlers versus furnaces. Proper coil selection that minimizes static pressure drop is crucial, as is ensuring airflow settings are correct. These metrics are key to diagnosing system performance.

Static Pressure as a Diagnostic Tool

Static pressure trends can indicate airflow problems or restrictions within the system. Bryan emphasizes the need to regularly measure static pressure to track changes over time, equating this process to monitoring one's blood pressure for health insights. Static pressure alone does not measure airflow but can be indicative of airflow issues when assessed alongside other metrics.

Show notes

In this short podcast episode, Bryan explains the science behind a common HVAC simile: static pressure is like blood pressure. He covers the similarities and differences between measuring static pressure during a service call or maintenance and a doctor measuring your blood pressure at a checkup.

Total external static pressure (TESP) should be measured every time you perform service or maintenance on a unit. The exact test port location will vary between air handlers and furnaces; the coil adds extra pressure drop in furnace applications. You need to pick a coil that has the lowest static pressure drop (same consideration as filters). Typically, the lower the pressure drop, the better. Make sure you use proper ports for static pressure testing when you do make those holes.

Static pressure isn't airflow itself. It can help diagnose airflow issues or give indications, but it doesn't measure the CFM. Static pressure is a balloon-type pressure exerted on the walls of the duct. Just as high blood pressure doesn't mean your heart is pumping more blood than it should, a high static pressure doesn't mean your blower is moving a lot of air; both can indicate restrictions.

You also don't want an extremely low static pressure, either. It could indicate that airflow is weak, just like a very low blood pressure indicates that the heart isn't pumping as it should. If you want to know your system airflow, you should use TEC's TrueFlow grid. However, static pressure is particularly good at measuring trends so that you can see where the numbers deviate from the norm for each individual system.

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Static Pressure is like Blood Pressure - Short #258