Arkansas HVACR NewsMagazine September 2019

S tate, National, Chapter News Tech News

[There are exceptions as one popular company offers a single media filter with a static pressure of only .06 on 5 tons (2000 cfm) of nominal air flow. This product must be used with horizontal air flow systems]. Most installation directions will instruct us on setting up proper airflow as it relates to static pressure. These instructions will caution the contractor to pay attention to transitions as well. Air will not flow beyond 22 degrees, so transitions must maintain a 5/12 ratio. In other words, we need one foot of depth for every 5 inches of width outside the equipment airstream. (Figure 2) Of course most evaporators today are designed to fit furnaces. These rules hold true on both the return and supply side.

That’s right Some manufacturers use a washable low density filter to keep wrenches and rocks out of the blower wheel. Think about it. The manufacturer has no idea of limitations on installed equipment, so they defer to the contractor. Contractors must be aware of filter performance for each brand and make selections for individual customers based on need. While most customers will be happy with the performance of a low maintenance deep pleated media filter product, there will be occasions where we must employ a top end combination electronic / media type filter. When these select products are used, please review the performance statistics. The best filter on the planet is a pane of glass; however it will allow “… you should assess air flow requirements and filter performance to insure adequate comfort and equipment protection” no filter! no air to pass by through. This is the problem with some dense filtering products on the market. They may offer superior filtering however low airflow and high energy demands on the equipment are the result. It bears repeating; if you have air handlers or furnaces that are over the three ton nominal mark, you will have to use two separate filters for proper operation in most instances.

(Figure 2)

End game- In summary we should use the fewest filters possible due to costs associated with replacement and lower energy consumption. Generally, two higher performance filters installed correctly