{"id":13110,"date":"2022-08-17T13:28:57","date_gmt":"2022-08-17T05:28:57","guid":{"rendered":"https:\/\/aircondlounge.com\/?p=13110"},"modified":"2024-03-26T12:06:01","modified_gmt":"2024-03-26T04:06:01","slug":"what-is-static-pressure-in-hvac","status":"publish","type":"post","link":"https:\/\/aircondlounge.com\/what-is-static-pressure-in-hvac\/","title":{"rendered":"What is Static Pressure in HVAC?"},"content":{"rendered":"\n
Static pressure is a common term used in HVAC. Not only homeowners but junior engineers often don’t understand what static pressure means. As static pressure is critical to the performance of HVAC systems, I thought a full explanation is needed.<\/p>\n\n\n\n
In HVAC, static pressure is the strength of a fan needed to deliver the required airflow. Ductwork components such as flexible ducts, return air grilles and air filters have static losses. Hence, a fan must have sufficient static pressure to overcome the static loss in order to deliver the required airflow.<\/strong><\/p>\n\n\n\n Many people often have low airflow problems in their HVAC system. Sometimes, it is due to insufficient fan static pressure. Hence, it is important to understand the static pressure in HVAC.<\/p>\n\n\n\n Air conditioners, blowers, exhaust fans and other types of fans have a certain amount of static pressure depending on their design and airflow capacity.<\/p>\n\n\n\n How much airflow can be delivered by a fan is directly proportional to its static pressure. The higher the static pressure, the greater the airflow subjected to the maximum capacity of the fan.<\/p>\n\n\n\n Conversely, if the fan static pressure is not enough, the fan may not even be able to supply the airflow as promised on its specification sheet or nameplate.<\/p>\n\n\n\n The airflow rate of a fan is always coupled with a static pressure value. For instance, at medium fan speed setting, the below fan model has an airflow rate of 875 cfm when the external static pressure is at 0.3 in.wc.<\/p>\n\n\n But, if the external static pressure raises to 0.8 in.wc, the same gas furnace is now left with only 670 cfm of airflow. That’s more than 20% reduction in airflow!<\/p>\n\n\n\n Therefore, it is important to select the correct fan static pressure based on the required airflow.<\/p>\n\n\n\n The unit of measurement for static pressure is commonly expressed as follow:<\/p>\n\n\n\n For unit conversion, 0.1 in.wg is equivalent to 25 Pa.<\/p>\n\n\n\n Static pressure is sometimes used interchangeably with external static pressure. External static pressure (ESP) is a more accurate term for the strength of the fan for actual airflow delivery.<\/p>\n\n\n\n There are two types of static pressures; a) internal static pressure and b) external static pressure.<\/p>\n\n\n\n Internal static pressure is the static pressure of the fan required to overcome the airflow resistance in the fan itself while external static pressure is the static pressure of the fan required to overcome the airflow resistance in the associated ductwork.<\/p>\n\n\n\n In the meantime, I would like to inform you that you can learn quicker by getting my HVAC Begin (eBook)<\/a> if you’re a beginner. But, if you have a year or two of experience, then I would suggest you consider my HVAC Basics (eBook<\/a>). Nonetheless, I encourage you enroll in my HVAC Beginner Course: 10 Days to Become Competent in HVAC if you want to equipped yourself with a complete set of basic HVAC skills.<\/p>\n\n\n HVAC Beginner Course<\/p><\/div>\n Learn the most basics and foundational HVAC skills including cooling capacity calculation, equipment selection, duct sizing, pipe sizing, exhaust fan sizing, controls, electrical and more.<\/p><\/div>\n HVAC Static Pressure Basics<\/h2>\n\n\n\n
Unit<\/th> Description<\/th> Standard<\/th><\/tr><\/thead> in.wc<\/td> inch of water column<\/td> Imperial Unit<\/td><\/tr> in.wg<\/td> inch of water gauge
(same as in.wc)<\/td>Imperial Unit<\/td><\/tr> Pa<\/td> Pascal<\/td> SI Unit<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n