All About Media Furnace Filters

Why are Furnace Filters so Important?

Replacement Furnace Filters

When you consider that the average Canadian breathes 12870.4 Litres of air each day, it makes sense to pay attention to your furnace filter. Indoor air quality is one of the top five environmental risks to health. In Ottawa, we spend as much as 80% of our time indoors, but most homeowners are unaware that the air inside their homes may be many times worse than outdoors. In fact, Indoor air pollution is two to five times worse, and at times may be up to one hundred times worse than the air outdoors.

DustmitesStandard furnace filters do little or nothing to protect us from common indoor air pollutants like dust mites, pollen, mold, radon, carbon monoxide, excessive carbon dioxide, and other chemical fumes (VOC’s). This air pollution contributes to lung disease, respiratory tract infections, asthma and lung cancer. Only a good furnace filter along with proper air exchange in the home can help reduce buildup of these potentially hazardous indoor air contaminants.

The most effective methods of improving indoor air quality are source removal, air cleaning with a furnace filter that has a high MERV rating , and increased ventilation air exchange with a Heat Recovery Ventilator (HRV). Controlling exposure to these indoor air allergens and environmental tobacco smoke in your home could prevent 65 percent of asthma cases among elementary school-age children.

NOTE: The average hardware store furnace filter is rated a MERV level of 1

Minimum Efficiency Reporting Values – MERV Ratings Explained

Furnace Filter Efficiency at Different Particle Sizes

MERV Value 0.3 – 1.0 Microns 1.0 – 3.0 Microns 3 – 10 Microns Types of things these furnace filters will trap
MERV 1  –  – Less than 20% Pollen, Dust mites,
Standing Dust,
Spray Paint Dust,
Carpet Fibers
MERV 2  –  – Less than 20%
MERV 3  –  – Less than 20%
MERV 4  –  – Less than 20%
MERV 5  –  –  20% – 34% Mold Spores,
Hair Spray,
Fabric Protector,
Cement dust
MERV 6  –  –  35% – 49%
MERV 7  –  –  50% – 69%
MERV 8  –  –  70% – 85%
MERV 9  –  Less than 50% 85% or better Humidifier Dust,
Lead Dust,
Auto Emissions,
Milled Flour
MERV 10  –  50% – 64% 85% or better
MERV 11 65% – 79% 85% or better
MERV 12 80% – 89% 90% or better
MERV 13 Less than 75% 90% or better 90% or better Bacteria,
Most Tobacco
Proplet Nuceli (sneeze)
MERV 14 75% – 84% 90% or better 90% or better
MERV 15 85% – 94% 90% or better 90% or better
MERV 16 95% or better 90% or better 90% or better

At Below Zero Heating & Air Conditioning, we believe every home should have at least a MERV 10 rated filter. We back this up by installing a MERV 10 Filter & Cabinet with every furnace installation in Ottawa.

See here for a more comprehensive explanation of MERV Values