High efficiency HVAC filters are used by businesses to not only provide a cleaner and healthier environment to the occupants, but also to protect equipment, processes and fixtures. Efficient HVAC filters shield against bioterrorism – one of the reasons why many establishments move air filtration to the forefront of their operating prerequisites. While facility managers are either upgrading their air filtration levels or moving to a new one, there are many others who are unable to unaware of the finer lines of air filtration, such as air pressure drop, and therefore, find it a challenge to select the right one for their needs.
What is Air Pressure Drop?
Air filters are inserted directly into the airflow path of the HVAC system to trap particles flowing through the system. If the air filter is dense and tightly knit, it may trap more particles and this is how the MERV of the filter is also calculated. A filter with high MERV or filtration density often slows down the airflow rate of the HVAC system which is called the air pressure drop.
How Does It Affect Filter Efficiency?
Higher Electricity Consumption
If a facility uses a highly efficient filter such as MERV 13 filter, it may result in higher energy consumption. When a system has a high air pressure drop, the HVAC unit needs to work harder, and therefore, may eventually end up consuming more electricity.
Filter Gets Dirty
The pressure drop created by air filters increases as the filters get dirty. Dust build-up provides less space to the air to flow through the filters and as a result the filters require frequent clean-up.
How to Go About Choosing a Filter?
Let’s look at how to find out whether a filter has a high pressure drop and whether it needs more surface area.
The pressure drop reading of a filter must not exceed the 20% of the maximum static pressure rated for the fan. The rating is present on the data plate of the HVAC equipment. If a fan, for instance, has a maximum static pressure rating of .25 inches, multiply it with .20 to get the ideal pressure drop. The pressure drop of the filter,in the example mentioned above need not be more than 0.05 inches of water column.
There may be instances when you may wonder why is it recommended to buy a high rated MERV filter if it lowers the efficiency of the system? It is important to understand that the problem doesn’t lie only with the filter. The amount of surface area of the filter and the size of the opening of the filter rack play a significant role in determining the pressure drop.
All the filters are not created equal and so even two filters with same MERV rating might have different pressure drops. Pleated filters, for instance, have a high MERV rating but a lower pressure drop than the other types of air filters. A restrictive air filter, on the other hand, has a high pressure drop has the potential to turn a 14 SEER system into an 8 SEER system. When choosing an HVAC system air filter, facility managers need to pay attention to the air pressure drop of the filter, MERV rating and the type of filtration application for which it will be used.
If you have any questions or need expert advice to select the best suitable air filter for your HVAC unit, feel free to speak with one of our representatives.