Furnace Filters and Air Conditioner Filters

We get a lot of callers asking us about air filters on their air conditioners and furnaces, what is the best furnace air filter, how frequently should you change an air filter, and how to change an air filter.

There are many videos on youtube.com that show you exactly how to find and install your furnace & AC filter – but if you get stuck, give us a call and we will be happy to walk you through it on the phone.


In Canada our homes are closed up for longer periods of time due to our longer winters for this reason a good filter is not only essential to proper operation of your furnace (and air conditioner) but it also becomes your first line of defense in keeping your family healthy.


What is an air filter for a furnace or air conditioner?

A typical air filter is simply absorbent fibers stretched across a frame (or accordion folded within a frame) that is designed to capture dirt, dust, pet hair, pet dander, bugs, lint, and more so that this stuff does not become air born in your home causing all kinds of issues – from breathing issues, skin irritation, eye irritation, not to mention the clean up of endless dusting, sweeping, vacuuming & moping once all that air born pollutants settle on your furniture & floors. But a good filter does even more, it removes spores & bacteria that can cause many common health issues.

The filter also helps improve operations of your furnace and air conditioner by filtering air born pollutants so they don’t get sucked back into your system clogging up your fan motors and coils. Gunked up coils reduce the amount of air that can be circulated and cause early wear and tear on your equipment that can lead to malfunction and/or failure.

Does my furnace or air conditioner have an air filter?

All furnaces and air conditioners have air filter. If you have a central air conditioner and furnace odds are you have just one filter that works for both the furnace and the air conditioner because they share the same duct work.

Is a standard air filter from a local hardware store good enough?

For many people the cheap standard air filter found in your local store is good enough provided you are changing it monthly.  Mike Holmes recommends every 3 months in his video but in Ottawa, if you are only going to use the cheap filters which clog quickly we recommend changing them monthly especially during cold winter months where the unit is running non-stop – better filters can be changed bi-monthly or quarterly.

If you suffer with allergies, asthma, skin irritations, or any other health issue that can be negatively impacted by air quality then you need more than the standard air filter. We recommend the Merv 11 filters that are deeper providing more surface area for capturing debris as well as bacteria & spores.  Because of the additional surface space between each fold the Merv 11 filter can hold much more debris and thus does not have to be changed as frequently – in fact you only need to change it every 6 to 8 months.

When you compare the standard filter (on the left) to the Merv 11 filter (as seen below) the difference is obvious. Of course this thicker filter will not fit where your standard filter goes – your duct work next to your furnace will require a minor modification to install the Merv 11 frame that holds the filter in place. If you would like to learn more about this give us a call and we can provide you with an estimate to upgrade your current venting.


Merv11 airfilter


Regardless of the type of filter you use, check it regularly.  A reminder on your calendar is all you need or you can sign up for our email notifications where we remind you via email when it is time to change your filters, turn off outside water before winter, and other important notices that affect local Ottawa home owners, if you have had services from us before and provided your email address you are already a Francis Plumbing Heating & Cooling GOLD Member).

What is IAQ?

IAQ stands for Indoor Air Quality and it refers to more than just air filters, it is also about the moisture levels in your home (humidifiers and de-humidifiers) bacteria killing devices that can be added to your furnace or air conditioners such as UV lights, and more.

Most people suffer with minor irritation caused by air conditioning in fact the numbers may alarm you.  Here is an article we found that although is US based (Canadian percentages are a bit higher) still gives a good overview of the problem:

Indoor Air Quality Facts (Article provided by ductpros.com in the US)

One of the main reasons for heightened public concern about deteriorating indoor air quality is the alarming increase in the number of children and young adults with severe allergies and asthma.

Air pollution in U.S. cities may cause twice as many deaths from heart disease as it does from lung cancer and other respiratory ailments, a surprising new study suggests. The statistical analysis was published in Circulation*, a journal of the American Heart Association.

According to the National Center for Health Statistics, 2001 National Health Interview Study, over 7.6 million children 5-17 years) and over 12.7 million young adults (18-44 years) suffer from asthma. The United States Environmental Protection Agency (EPA) ranked indoor air pollution among the top five environmental dangers to the public. EPA research also concluded that indoor air can be two to five times (and sometimes as much as 100 times!) more polluted than the WORST outside air! Since research indicates Americans spend 90% their time indoors, it’s no wonder that asthma and allergy suffering is on the rise.

Recent articles are linking asthma to various possible indoor air pollution situations. The Chicago Tribune (9/26/04) published a comprehensive article on the astounding 86% increase in asthma cases between 1980 to 1996. About 5,000 people die from asthma related issues. Causes, such as cigarette smoke exposure, allergens people breathe, and even children’s activity levels are being investigated.

One ounce of dust contains nearly 42,000 living dust mites. Each mite is expelling 20 fecal pellets every day into the air you breathe.

USA Today (9/30/04) re-ported that household chemicals are linked to the increasing incidence of children’s asthma. The many chemical compounds in today’s building materials (vinyl, pressboard, paint and polyvinyl chloride to name just a few) leach out of their source products and become part of today’s home indoor air contaminants.

Another allergenic irritant, the dust mite, thrives in warm, humid conditions and feeds upon dead skin flakes shed by humans and pets. Each person can shed up to 700,000 skin scales per day creating an abundant food source for this prehistoric looking nemesis to good health. Approximately 10 to 15 percent of the population suffers from an allergy related to dust mites with most allergic to the airborne, breathable dust mite feces and not the dust mite itself. About 40,000 dust mites can “thrive” in only one ounce of dust, so imagine how many dust mites may live in even the cleanest homes!

Allergenic particles such as pollen, dust, mold spores, fungi spores, tobacco smoke, dust mites, pet hair and pet dander all contribute to poor indoor air quality. Additionally, common household furnishings such as draperies, carpeting, wallpaper, paints, stains and furniture may continue to “off-gas” potentially toxic fumes for a long time after application or installation. Another health problem associated with a tight home is the relative ease by which viruses and bacteria brought into the home by one person can readily transfer to other people in the home.

Research indicates that most people spend about 90% of their time indoors. The EPA ranked indoor air pollution among the top five environmental dangers to the public.

Heating and air conditioning ducts which are dark, damp and rich in “nutrients” provide an excellent breeding ground for mold, fungi and dust mites which can spread rapidly when these ducts are in use to heat or cool the home. Poor ventilation and dirty filters are also major contributors to unhealthy contaminates in the home. Mold and fungi can cause “discomfort”, infections and commonly trigger allergic reactions. A Mayo Clinic study found that “Allergic Fungal Sinusitis” was diagnosed in 93% of 101 consecutive surgical cases with CRS (Chronic Rhino-sinusitis). (footnote 1) Over 36 million Americans suffer from Chronic Sinusitis.

Why has indoor air quality substantially deteriorated over the last 30 to 40 years? Because changes in new home construction practices that evolved out of the 1970’s energy crisis created “tight homes” that are tightly sealed, heavily insulated and very energy efficient. While these new construction practices helped conserve energy which is good for our national security, they also “locked-in” allergenic particles, infectious agents and toxic compounds, which are bad for the health and well being of our families. Your beautiful, “clean” home could be a major source of airborne contaminates that could prevent you and your family from feeling “healthy” and “energetic”.

If these facts are making you feel a bit queasy, it should come as no surprise for you to learn that many Americans indicate they feel “less well” today when compared to several years ago. Yet many people don’t know why they feel worse today or why more children suffer from allergies and/or asthma than 30 or 40 years ago. Research indicates that percentage wise, there are more people who have allergies today than there were 40 years ago. Why? Again, the answer may be found in an analysis of post 1970s tight home construction practices and the increased exposure to allergens and toxic compounds which build up in the body on a cellular level in people living in a tight home.

The bad news is that these conditions exist, to some degree, in every home no matter how clean they are… the good news is that there are ways to control them.

What are the effects of “off gases” that accumulate in tight homes and how do unknowing parents actually create an environment which may harm their children? Consider this scenario… a young couple receives wonderful news that they are expecting their first child. Of course, they’re very excited so they prepare a new special nursery for their baby’s arrival. They paint the walls, put up wallpaper, buy new carpeting, new drapes and new baby furniture. Unfortunately, EVERY ONE of these materials can emit toxic gases which can cause headaches, dizziness and respiratory symptoms due to nose and lung irritation. If parents knew they were taking their precious child from a hospital, one of the cleanest places on earth, with perhaps the best indoor air quality available, and placing their child into a potential toxic environment… it would make them sick! (If it hasn’t done so already!)

According to information from the American Academy of Pediatrics, children are more vulnerable than adults to many airborne contaminants. The cellular immaturity of children and the ongoing growth process account for this elevated risk. Since children breathe more rapidly and inhale more pollutant per pound of body weight than do adults, even minor irritation caused by air pollution, which would produce only a slight response in an adult, can result in a dangerous level of swelling in the lining of the narrow airways of a child.

Increased exposure to air pollutants during childhood increases the risk of long-term damage to a child’s lungs. As a nation we have recognized the benefits of drinking clean water as we spend over $7 billion dollars annually on bottled water.

It is suggested that we drink approximately two quarts of clean water each day to maintain optimum body conditions. By comparison, we inhale approximately 15,000 (or more) quarts of air each day. Although drinking clean water each day is important, how important is it to a healthy lifestyle to consume “clean air”?

Original article can be found at: http://www.ductpros.com/indoor-air-quality.html

To receive a free consultation to go over your current indoor air quality options call 613-224-0041 or pop us a question in the chat box!


*Air Pollution and Cardiovascular Disease | Circulation, 1 Jun 2004