A Guide to HVAC Filters
It’s time we all gave our HVAC filters a little more respect. Call
an HVAC technician and one of the first questions they ask is “When
was the last time your cleaned or replaced your filters?”
We might prioritize this chore if we understood what HVAC filters are designed to do.
FAQs About HVAC Filters
Why Do HVAC Filters Matter?
HVAC filters aren’t much to look at, but they’re critical to
prolonging the life of your equipment and maintaining healthy
indoor air quality.
Filtration takes place when expended air is sent back into the system for
conditioning and redistribution. Air cycles through the filter many times
a day, especially during summer and winter, when HVAC use is heaviest.
As the air is forced through, the filter traps materials and contaminants
that would otherwise keep circulating, such as:
Dust, lint, and cloth fibers
Particles of wood, metal, and other materials
Pet hair and dander
Pollen and other allergens
Mold spores, bacteria, and other harmful microorganisms.
The Environmental Protection Agency reports that indoor air is significantly
more polluted than outdoor air. That’s especially scary, considering
that most of us spend around 90 percent of our time indoors.
What Happens If I Forget to Replace My Filters?
When filters clog with dust and debris, particles in the air find their
way into sensitive HVAC components. That puts the system at risk for malfunction.
At the very least, your equipment has to work harder to get the job done.
Inadequate airflow also results in sluggish or uneven heating and cooling.
The rooms farthest away from the unit are too hot or too cold. Some have
stale, unpleasant air quality because of poor circulation. Dust, moisture,
and odors seep into carpeting and upholstery.
That’s the least of your worries. A dirty air filter might trigger
sneezing, coughing, watery eyes, or asthmatic symptoms.
What Are MERV Ratings?
HVAC filters are so important that the American Society of Heating, Refrigerating,
and Air-Conditioning Engineers developed a rating system for them. The
Minimum Efficiency Reporting Value, or MERV, lets consumers know how well
a filter will do its job.
For most home systems, values range from 1 to 16, with 16 being the most
efficient at capturing the smallest airborne particles and other contaminants.
Particle sizes of 0.3 to 10.0 microns are factored into the rating.
The U.S. Department of Energy recommends MERV 13 filters for residential
use. Those assigned higher values — such as for use in hospitals
and other exceptionally clean environments — might strain a home
heating system that’s not designed for the highest-efficiency filters.
Here are some examples of MERV values:
Values 1-4: Trap less than 20 percent of standing dust, dust mites, pollen, spray
paint dust, carpet fibers, and other particles.
Value 5: Traps 20 to 34 percent of things like mold spores, cement dust, hair spray,
and fabric protector. Value 8 traps 70 to 85 percent.
Value 12: Traps 80 to 90 percent of lead dust, humidifier white dust, auto emissions,
and other pollutants.
Values 13-16: Trap anywhere from 75 to 90 percent of substances like tobacco smoke,
bacteria, and droplet nuclei. Tuberculosis, measles, some flu viruses,
and other health hazards are transmitted through droplet nuclei when infected
people sneeze, cough, or even talk.
The wrong filter can do more harm than good. An
HVAC pro can clear up any confusion and recommend the best MERV value for your
How Do Filter Types Differ?
Here’s a brief breakdown of your options:
Fiberglass filters are disposable and inexpensive. They’re better at protecting your
HVAC equipment than cleaning your air.
Pleated cotton or polyester products have folds for greater surface area. That means they can capture more
particles, so you can go longer between replacements.
Washable air filters cost more than disposable products, but you’ll save on replacement
costs. To avoid mold and bacteria growth, allow plenty of time for washed
filters to dry.
Electrostatic filters are multilayered. Dust and airborne particles are positively charged when
air passes through the filter. The particles then attach to the next layer
and bind together. They eventually grow too big to escape the filter.
Many electrostatic filters are reusable.
High-efficiency particulate air filters, or HEPA filters, capture up to 99.97 percent of contaminants. They’re
ideal for people with respiratory problems or severe allergies.
UV filters aren’t designed to screen dust and other particles. Instead, they
augment your filtration system by using ultraviolet light to kill viruses,
bacteria, and other dangerous microorganisms.
How Often Should I Replace My Filter?
Most manufacturers and contractors recommend washing or replacing your
filter every 30 to 90 days. If you live in a dry, dusty environment or
have an 80-pound dog that sheds, you can expect dirt to build up faster.
Check your filters about once a month.
How Will I Ever Remember to Replace My Filter?
The easiest way is to upgrade to a smart thermostat that does the remembering
for you. When the filter starts to restrict airflow, an indicator light
eliminates the guesswork.
Some folks check the filter every month when they pay the energy bill.
Others set reminders on their smartphones or stockpile replacement filters
in a conspicuous spot.
However you get it done, routinely maintaining your filter will save you
a fortune in repairs and energy costs. You’ll also stay more comfortable
and breathe easier in your home.
Professional HVAC Services in Northern Virginia and Maryland You Can Trust!
My Plumber Heating, Cooling and Electrical for your cooling and indoor air quality needs this summer. To schedule
your appointment, call (844) 294-8999.