Your Guide to Understanding HVAC Air Filter Selection and Ratings
Your Guide to Understanding HVAC Air Filter Selection and Ratings

Your Guide to Understanding HVAC Air Filter Selection and Ratings


Be part of our exclusive Construction Professional list and get exclusive discounts and monthly executive summary

* indicates required
( ) - (###) ###-####
Subscription to Newsletter


* indicates required
Subscription to Newsletter *
* indicates required
Subscription to Newletter *

Effective air filtration delivers primary defense for commercial building occupants as well as HVAC equipment against any pollutants often generated within the building and from the air drawn from the HVAC system. That is the main reason why it is crucial to select the right HVAC air filter. The simplest HVAC air filter makes a huge difference in the building’s energy costs, IAQ, and the HVAC system’s performance.

Air filters exist to keep the parts inside the air handler much cleaner and running smoothly. The performance of filters commonly indicated by their ratings. Higher ratings indicate that the filter is much more effective at holding and trapping smaller airborne particles. With today’s higher standards when it comes to air filtration, it’s possible to provide purer, cleaner air and minimize indoor air quality (IAQ) problems.

Here is a guide for you to further understand HVAC filter considerations, different filter ratings and so on.

The Filtration Efficiency Equation


The very first step in determining the right type of HVAC filter needed is pinpointing the sizes and types of specific pollutants in the building. Various particles cause IAQ issues, from fumes and submicron smokes to larger dust particles. Removing all airborne contaminants is not practical in many facilities. Therefore, once pollutants are distinguished, it is the right time to look at filter efficiency. 

Filtration efficiency refers to the process of how well the filter cleans indoor air by eliminating airborne particles. Low-efficiency filters (ranging from twenty-five percent efficiency) are commonly used to keep dust and lint from clogging the HVAC system’s cooling and heating coils. Moreover, both medium and high-efficiency filters (up top ninety-five percent efficiency) are commonly used to eliminate pollen, soot, bacteria and other small particulates.

Take note that when choosing the right filter for the application, higher isn’t always better:

  • Using a particular air filter with a higher MERV rating compare to what the manufacturer has recommended may impair the actual performance.
  • The smaller pores, especially in more highly-rated air filters, may create resistance to airflow.
  • If air filters that are used in the HVAC system aren’t designed to handle the resistance, it lowers the system’s efficiency. 
  • Air filters that cannot handle resistance decrease indoor air quality, putting a strain on the HVAC system’s fan.

Moreover, you need to also focus on implementing project management for construction. It is most likely what every HVAC contractor does when projects and tasks tend to be overwhelming. Projects, tasks, and the crew members involved are best managed when it is being implemented.

What are the Two Different HVAC Filter Ratings?


While Minimum Efficiency Reporting Value (MERV) is the standard rating system for HVAC filters, there are still other commonly used scales. Here’s what you need to know as an HVAC tech about the three major filter rating systems.

1. Minimum Efficiency Reporting Value – MERV


MERV is the standard rating system. It is defined in the ASHRAE standard (52.2), specifying the performance required to meet each level and the testing required. Higher-MERV filters can remove more particles from the building’s air. The standard fiberglass 1-inch filter is commonly a MERV 2. Presently, MERV-16 is the high-end scale among all. It used to be twenty, but ASHRAE dropped the level sixteen years ago for some valid reasons.

Below are various MERV ratings:

  • Between 1 & 4: Low-grade HVAC filters like washable filters or spun-fiberglass often carry a MERV rating ranging 1 to 4 at best. While these filters trap carpet fibers, pet hair, or other large debris, they are considered ineffective in improving IAQ (indoor air quality).
  • Between 5 & 8: Filters with this rating typically deliver an improved filtration and trap particulates between three to ten microns.
  • Between 9 & 12: The filters with this rating provide a much more superior filtration in different applications, trapping lead dust and auto emissions.
  • Between 13 and 16: Filters that fall in these MERV ratings can trap bacteria, tobacco smoke and any particulates less than 0.30 pm particles.

2. Microparticle Performance Rating – MPR


MPR is developed by a company having a financial interest in the sales of filters. It’s none other than 3M, the creator of the Filtrete line of filters. This rating system typically measures the filters’ effectiveness, especially on how it captures the smallest particles having the MERV scale: 0.3 to 1.0 microns. 3M indicates that MPR has the ability to capture even the tiniest particles between 0.3 and 1 micron by size.

Chances are better if the filter can capture tons of small particles because it might also capture even the larger particles. They do measure large particles and you can download a table of captured efficiency data where there’s a comparison between MPR and MERV. The MPR system uses a numerical scale where higher numbers indicate better filtration. The scale under this rating system, however, uses larger numbers. Also, the basic filter is often rated at one-hundred, while the most efficient filter is rated at 2800. 

The MPR-2800 is qualified as a MERV-14, which only means that the best MPR filter doesn’t qualify when it comes to the highest MERV rating. Filters that have MERV rating have always been the very first choice. 

Recognizing ASHRAE HVAC Standards for Air Filters


Depending on the particle size and the method the test was performed, the manufacturers may easily skew efficiency results. That is why they need to consider these variables when choosing a filter:

  • Temperature limitations – how a filter performs at certain application temperatures
  • Moisture resistance – how high moisture and humidity affect the filters
  • Flammability – how a filter functions in flammability tests

Furthermore, to help HVAC contractors like you who specify filtration systems for renovation or new projects, ASHRAE developed and issued the following:

AHSRAE Standard 52.2 Method of Testing General Air-Cleaning Devices for Removal Efficiency by Particle Size.

This standard mainly forces manufacturers to follow a certain prescriptive testing methodology to identify the system’s MERV rating. Whenever comparing system options, system designers and managers can immediately compare the manufacturers’ MERV ratings with certainty and confidence. 

ASHRAE Standard 62.1 Ventilation for Acceptable IAQ

The standard specifies minimal ventilation rates and other measures like MERV ratings, particularly for existing and new buildings. For most institutional and commercial buildings, it only means that the filtration system must have a minimum MERV rating of 6. However, depending on the facility and occupancy, MERV ratings should be as high as 20.

Consider also implementing project scheduling management while you’re providing any HVAC services to your client. You and your team can depend mainly on advanced implementations and construction techs. Ensure to deploy Pro Crew Schedule at work.

What HVAC Techs Should Do to Maintain the Filtration System?


Understanding the two ASHRAE standards as mentioned above can help you achieve the maximum level of efficiency. However, if you’re not properly maintaining the filtration system, chances are energy costs may increase while IAQ suffers. While it is generally easy to operate and maintain the filtration system, most facilities cannot handle such tasks properly. Like you, an HVAC tech with building managers can take only three steps to ensure the systems operate correctly. 

1. Specification

Effective maintenance should start with selecting the size and type of the filter for a particular application. That only means HVAC technicians should firmly understand the level and type of pollutants generated inside the space where the system serves. Operational requirements must also be taken into consideration while project task management is being a priority.

Filters may come with MERV ratings ranging from 1 to 16. Though 6 is the suggested minimum MERV level for most commercial buildings, choosing one with a much higher rating may not be crucial for the application. It might increase the fan’s energy requirements.

2. Replacement 

Some buildings replace the filters on a certain set of schedules, like every thirty, sixty, or ninety days. Others tend to replace them when clogs tend to be noticeable or whenever a building occupant is inquiring and complaining about the HVAC system’s performance. Installing sensors to precisely measure the pressure drop across the filters is considered a better approach to applying. Whenever contaminants buildup, the pressure drops across the filter tend to increase.

There are various types of HVAC filters available on the market today. In most commercial buildings, the ideal filter choice is the medium-efficiency pleated filter such as MERV 7-8. This rating has a larger filter media area. An HVAC professional like you should keep in mind that larger filer media areas can be more cost-effective than smaller ones. 

3. Use Subcontractor Scheduling Software

Delivering HVAC services to your customers and managing the delivery team has its unique challenges. Good thing that Pro Crew Schedule is designed with the HVAC industry needs in mind. Many contractors are turning to this software solution because of its all-in-one approach in resolving their many challenges.  

It should come as little surprise that Pro Crew’s HVAC Contractor software has plenty of advantages. It fits your HVAC business’s needs and the many challenges you face with your team in the industry and serving your clients. Make sure to request a live demo to experience all the fantastic features Pro Crew Schedule offers. It’s FREE!

Here are the many benefits of this cloud-based software.

  • One-service platform
  • Simple workforce management
  • Better construction crew management
  • Real-time updates
  • Time-tracking 
  • Empowers your crew members
  • Greater access to data and information
  • Easy accessibility
  • Easy to explore and user-friendly

Key Takeaways


More powerful pleated filters can now do a much better job in filtering compare to the past. This is due to the fact that modern designs have much lesser airflow issues at high MERV levels. Hence, they are much more practical compare to the other filters at improving indoor air quality. Make sure you take all the considerations for air filters when selecting a filter. You should understand MERV and learn how to maintain the filtration systems best.

Leave a Comment

Your email address will not be published. Required fields are marked *

Scroll to Top