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Buying A Furnace Filter: Finding Your Fit with MERV Ratings

Jan 11, 2017

Furnace Home Improvement
Furnace Components

Modern furnaces and HVAC systems are often so engineered and streamlined that they may seem maintenance-free. While this is practically true for some models, almost all furnaces require the manual upkeep and replacement of filters. By just removing the old filter and inserting the new one, you will see an improvement in your property’s temperature control, air quality, and utility usage. But when you browse online or in-store, there are so many filter brands and types from which to choose! If you need help finding the right furnace filter, read on for Romaniuk’s introduction to fit and MERV ratings.

Filter Types

All of the varieties below come in a wide range of standard sizes that fit most furnaces. To be sure, either check for a size listed on your furnace or simply bring along an old filter to compare. Remember: you can change the type of filter, but not the size.

Pleated Disposable Options

Have paper or cardboard frames and pleated, polyester filter panels. Moderately priced, they are good for approximately three months and should be checked monthly for large debris.

Fiberglass Disposable Models

Fiberglass disposal models are the most affordable, but they tend to be less durable and not as useful for filtering out dust or allergens. Check and replace more often than pleated filters.

Washable Reusable Filters

Sometimes called “permanent–” are long-lasting alternatives thanks to their sturdy plastic or aluminum frames. Also, these filters can be washed easily with water every two to three months resulting in a lifetime of up to five years.


Regardless of type or material, all filters are subject to a rating system that identifies how effective and efficient they can be if maintained properly. The minimum efficiency reporting value or MERV rating system was conceived in 1987– from 1 to 20; the scale defines how small of a particle can pass through the filter. The list below outlines the contaminants and applications of specific MERV ranges.

MERV 1 – 4:

MERV 1-4 Filters are capable of blocking fabric or carpet fibers, spray paint or sanding residue, large insect debris, dust mites, and pollen. Used when minimal filtration is required– such as window A/C units and residential HVAC systems.

MERV 5 – 8:

MERV 5- 8 Filters can filter out fine dust like pudding mix or cement dust; fine sprays like dusting aid, hairspray or fabric protector; pet dander; dust mite debris; mold or spores. Used in paint booths, industrial workspaces, commercial buildings and higher quality residential HVAC systems.

MERV 9 – 12:

MERV 9 – 12 Filters prevent the spread of particles smaller than 3 micrometers down to 1.0 μm– nebulizer droplets, humidifier dust, industrial fumes from auto emissions and welding, milled flour and the bacteria responsible for pneumonia-type illnesses. Used in medical labs, higher quality commercial HVAC, and premium residential systems. Higher ratings than MERV 12 can restrict the airflow of residential furnaces too much to be useful, including popular HEPA filters.

MERV 13 – 16:

MERV 13 – 16 Filters eliminate most paint pigments and cosmetic powders, most insecticide dust, most smoke, cooking oil, sneeze spray (droplet nuclei) and all bacteria. Likely the highest rating available to consumers. In premium commercial HVAC systems, inpatient and surgery areas of hospitals and smoking lounges this is the rating used.

MERV 17 – 20:

MERV 17 – 20 removes all smoke, viruses, carbon dust and sea salt from the air. This heavy duty filter is used for “cleanrooms” in manufacturing pharmaceuticals and electronics.

As you can see, there is a lot to choose from– but most property owners buy one type of filter and stick with it for the life of the furnace or HVAC system. If you have any questions or concerns about your filter needs, contact or visit Romaniuk Heating & Air Conditioning.

**Chart courtesy of United Filters (Source –