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What is Pressure Drop?

Pressure Drop DiagramThe term “Pressure Drop” gets used a lot in the indoor air quality industry, but it isn’t always well defined. The Wikipedia definition of pressure drop is as follows:

Pressure drop is a term used to describe the decrease in pressure from one point in a pipe or tube to another point downstream.

This applies to Indoor Air Quality (IAQ) when we talk about air filtration. When air is drawn through an HVAC system with a filter installed, that filter will create some resistance to the airflow. As a result, the difference in air pressure in the ductwork on one side of the filter versus the other side of the filter is what HVAC professionals refer to as pressure drop. Too much Filter clogged with dustpressure drop indicates too much resistance to the airflow and that an HVAC system is struggling to process the air. This wastes energy and accelerates wear and tear, as the blower has to work harder and run longer to achieve the desired temperature at the thermostat. The trick is to install an air filtration system that is effective without creating excessive pressure drop such as an Ultravation ProgressiveMedia Whole House Air Cleaner.

However, dirty filters are still the most common cause of excessive pressure drop. That’s why it is so important that filters are changed on a regular basis. When you use Ultravation ProgressiveMedia™ air filters, it is typically best to replace a 5” thick pleated air filter every 6 months. If you live in a particularly dusty climate you may need to change it more often. If you have acute allergies, monitor your filter and symptoms closely to determine what your ideal replacement schedule should be. For people with 1” filters in their air handler, the filter usually needs to be replaced once a month.