How to Calculate Static Pressure in HVAC System?

If you work in the HVAC industry, you know how important it is to maintain proper static pressure in HVAC systems. Understanding how to calculate static pressure in HVAC system is crucial for ensuring optimal performance and efficiency.

Static pressure refers to the resistance of airflow through the system, and it can have a significant impact on the system’s performance and efficiency.

Understanding how to calculate static pressure is crucial for ensuring that HVAC systems function as intended, providing comfortable indoor environments while staying energy efficient.

In this article, we will explore how to calculate static pressure in HVAC systems, including the necessary tools and formulas.

By learning how to calculate static pressure, HVAC professionals can identify and address issues with airflow, optimize system performance, and improve overall energy efficiency.

How to Calculate Static Pressure in HVAC System?

Before we take you into the calculations we suggest you should get some basic knowledge of static pressure, So firstly it is important for you to understand what static pressure is and why it’s essential for your HVAC systems.

In simple terms, static pressure is the resistance that air undergoes as it flows through the ductwork and equipment of your HVAC system.

The resistance is mainly formed by the frictional force of the air against the surfaces of the ducts, fittings, and equipment, and you can measure these in inches of water gauge or pascals also marked as (W.g) and (Pa).

If the static pressure in your HVAC system gets too high or too low, it can result in affecting its airflow rate, and energy efficiency, and reducing the overall performance of the system.

Higher static pressure can also affect you because it can increase energy consumption, reduce airflow, and even can damage the equipment of your HVAC system.

On the other hand, a lower static pressure can lead to insufficient airflow and poor performance. Hence it makes monitoring and maintaining the static pressure of your HVAC system within the optimal range an essential task for you.

Measuring Static Pressure

So here are some tools you will need to measure the static pressure of your HVAC system.

You will be needing a manometer and pitot tube, you will use a manometer to measure the pressure from the pitot tube and the pitot tube will come in handy for measuring the static and velocity pressure.

So start by taking readings of several points of your HVAC system, which will include the supply and return ducts and the filter. You need to insert the pitot tube into the ductwork, and then connect the manometer to the tube.

After that, the manometer will show you the static pressure reading that you have to note down to calculate the total external static pressure (TESP) is the sum of the static pressure on the supply and return sides of your HVAC system and defines the total resistance of the airflow within.

Calculating Static Pressure

So now to calculate the (TESP) or the total external static pressure of your HVAC system, you have to add up the static pressure readings with the supply and return sides as we told you in the above paragraph.

We will also suggest you should compare your (TESP) measurement to the manufacturer’s guidance to ensure that they fall within the optimal range.

If your (TESP) results are too high or too low, this could be an indicator of a problem in your HVAC systems ductwork, filter, or other components.

Using the (TESP) method you can diagnose a lot of problems and can help you identify and resolve them because they might be affecting the performance and efficiency of your HVAC system.

E.g. if the (TESP) is too high, it’s an indication that your ductwork is too small for the airflow or the airflow is being obstructed which is limiting the airflow.

If the (TESP) is too low, it’s an indication that the filters are dirty and need to be deeply cleaned or need to be changed as soon as possible, or either it could indicate that the ductwork is over-sufficient for the needs of your HVAC system.


In conclusion, calculating static pressure in HVAC systems is a crucial part of maintaining optimal system performance and energy efficiency.

By measuring and analyzing static pressure, HVAC professionals can identify issues with airflow and make necessary adjustments to ensure that the system is functioning as intended.

While calculating static pressure may seem daunting, you can perform it using basic formulas and readily available equipment.

By mastering this skill, HVAC professionals can ensure that HVAC systems provide comfortable and healthy indoor environments, reduce energy costs, and promote sustainability.

If you work in the HVAC industry or are responsible for maintaining HVAC systems, be sure to consult with a licensed professional and invest in the necessary tools and training to accurately calculate static pressure and optimize system performance.

Leave a Reply