Total External Static Pressure

Total external static pressure (TESP) is the measurement of the resistance to airflow in an HVAC system, and it includes the static pressure losses that occur in the supply and return ductwork, air filters, grilles, and registers. Measuring TESP is crucial in determining the system's overall performance and identifying potential issues that may lead to inefficiencies.

To measure TESP, you will need a manometer, which is a device that measures pressure differences between two points. Here are the steps to measure TESP:

1. Turn off the HVAC system and make sure all dampers are closed.
2. If established, locate the pressure taps on the supply and return sides of the HVAC system. These are typically located on the plenum or the main ducts.
3. Attach the hoses from the manometer to the pressure taps, making sure they are connected securely and without any leaks.
4. Turn on the HVAC system and set it to run at its normal operating conditions.
5. Record the pressure readings on the manometer for both the supply and return sides of the system.
6. Calculate the TESP by subtracting the return pressure reading from the supply pressure reading. The result is the TESP in inches of water column (in. w.c.).
7. Compare the TESP to the manufacturer's recommended TESP for the system. If the TESP is higher than the recommended value, it may indicate that the system is not operating efficiently and may require further inspection and adjustments.

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