When it comes time to consider proper filtration for any HVAC system, a few things to keep in mind include the correct filter size, filter material, filter type, the environmental conditions the filter is used in, and MERV ratings (see more on that below). Filters in any heating and air conditioning system are extremely important but often neglected. They shouldn’t be, and the information presented here can provide a better understanding of their use and importance.
| MERV |
Particle Size (micrometre) |
Typical Controlled Contaminant | Typical Application |
|---|---|---|---|
| 1-4 | > 10.0 μm | Pollen, dust mites, cockroach debris, sanding dust, spray paint duct, textile fibers, carpet fibers | Residential window AC units |
| 5-8 | 3.0-10.0 μm | Mold, spores, dust mite debris, cat and dog dander, hair spray, fabric protector, dusting aids, pudding mix | Better residential, general commercial, industrial workspaces |
| 9-12 |
1.0-3.0 μm |
Legionella, humidifier dust, lead dust, milled flour, auto emission particulates, nebulizer droplets | Superior residential, better commercial, hospital laboratories |
|
13-16 |
0.3-1.0 μm |
Bacteria, droplet nuclei (sneeze), cooking oil, most smoke and insecticide dust, most face powder, most paint pigments |
Hospital and general surgery |
| 17-20 | <0.3 μm | Virus, carbon dust, sea salt, smoke | Electronics and pharmaceutical manufacturing clean room |
Generally, filter specifications are determined by your central heating or air conditioning unit and the walls, ceilings or return vents within a building. Information to consider on filter size and material include the following:
Air Filter Size
This is important for the proper and efficient operation of a system. A filter that is too large will have to be forced into place and will most likely not fit properly, while a filter that’s too small may allow for airborne particles and contaminants to pass through and into the building’s environment. Either of these issues can result in the HVAC system needing to work too hard to perform the job. Determining the filter size is easy, as most often the filter size is printed on the filter being replaced (e.g., 16" x 25" x 1") and is commonly referred to as the “nominal size.” If the filter isn’t marked, measure the size top-to-bottom, side-to-side, as well as the thickness. This is usually an even measurement and considered the “actual measurement”. However, this could be slightly smaller than the marked or nominal size (e.g, 15½" x 24¾" x ⅞"). Regardless of how it measures up, the most important thing is that the filter fits properly in your system, with all four sides touching the filter frame.
Air Filter Material
Several different types of HVAC system filters are available including standard, pleated, carbon, electrostatic, HEPA, and electronic. Standard, pleated, and electrostatic filters are most commonly used in today’s systems.
Standard air filters, made of spun fiberglass with cardboard frames, have the capacity to remove roughly 10% of airborne pollutants. The most inexpensive type of filter, they should be changed every 30 days.
Pleated air filters, with filter material shaped like an accordion (providing greater surface area), have the capacity to capture roughly 35-40% of air contaminants. With the larger surface area providing enhanced efficiency, pleated air filters last longer than standard air filters and should be changed every 3 to 4 months. Generally, these cost slightly more than standard filters.
Electrostatic filters use an electronically charged media to capture particles and contaminants as air passes through. These filters may be pre-charged or are activated as the air flows through the filters’ multiple layers to create the charge. Significantly more expensive than standard or pleated air filters, electrostatic filters should be replaced annually.
Carbon air filters, as the name suggests, contain absorbent carbon particles enclosed in polyester fibers which filter fumes and odors as air flows through. Slightly more costly than a pleated air filter, carbon air filters are disposable and require changing every 3 to 4 months.
Electronic air cleaners provide some of the highest levels of filtration in a more permanent solution. The cleaners work on a principle similar to electrostatic filters, with particles and contaminants “zapped” as they pass over electronically charged plates. Recommended for those suffering from allergies, electronic air cleaners are more expensive than any of the other filters and often require professional installation and cleaning.
|
|
|
|
Whether the need is for a flat standard air filter, a carbon air filter, or any of the thousand others Zoro carries, we have what you need to keep your environment clean and healthy.
Product Compliance and Suitability
The product statements contained in this guide are intended for general informational purposes only. Such product statements do not constitute a product recommendation or representation as to the appropriateness, accuracy, completeness, correctness or currentness of the information provided. Information provided in this guide does not replace the use by you of any manufacturer instructions, technical product manual, or other professional resource or adviser available to you. Always read, understand and follow all manufacturer instructions.