Furnace filters... not to be neglected!

Your furnace has probably been working overtime since the fall. But did you know that it does more than heat your home? In addition to keeping your house warm and cosy, it cleans the air you breathe. Furnaces are equipped with various types of filtration systems that trap particles generated by cooking, smoke from tobacco and fireplaces, animal fur, dust from household activities as well particles blown in from the outdoors. It is therefore vital that you have your filter checked when your home furnace is being serviced. If the filters are not cleaned or changed, you may be breathing a high level of dust as well as compromising the performance of the furnace during the 12 to 15 weeks of winter.

Types of filters
There are several types of filters on the market: fibreglass, electrostatic precipitator, electronic and pleated. Performance varies greatly, depending on the type and quality of the filter you use.

Fibreglass filters: inexpensive but not very effective
Fibreglass filters, which have been on the market since the 1950s, are the least effective option available. According to a study conducted by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), they are only between 3% and 5% effective! And although performance is sub-standard, this type of filter should generally be changed every two to three weeks. In addition, they cannot be washed and must be discarded after use. They can be purchased for a mere $1 or a little more. The question here is: even though they are quite cheap, are you really saving any money? And how just environmentally friendly are they if they are to be discarded?

Electrostatic precipitator filters: much better
As the name indicates, this type of filter uses electrostatic charges to trap dust. There are two types. The first polarizes and traps dust by using electricity to create an electrostatic field. The second type does not use any electricity. Like a comb that is rubbed, its components trap the dust and particles suspended in the air.

The results obtained with these types of filters are superior to those provided by the fibreglass filter; however, given their efficiency — which can be as high as 60% — they tend to become clogged up quite quickly. They must therefore be cleaned often. Some are even washable; however, this decreases their filtration capacity. As with fibreglass filters, they are not permanent and, in order to ensure good air quality, it is recommended that they be cleaned once a month and changed every three months. This type of filter should cost $25 and more. Good-quality filters are certified by the ASHRAE.

Electronic filters: superior performance
Electronic filters eliminate the dust in the air almost entirely. They do have a disadvantage though; they produce small quantities of ozone during operation and this can aggravate certain respiratory problems, such as asthma. Electronic filters are permanent and can be cleaned. In order to ensure maximum efficiency, they must be cleaned often. Unfortunately, in practice, we tend to overlook filters and this increases the impact of the ozone. For this reason as well as the high cost, professionals and consumers tend to avoid using this technology. The filter alone could cost up to $250 and you would have to pay approximately $900 to have it installed. There are equally effective, and much less expensive, filters on the market.

Pleated filters
Pleated filters offer superior-quality filtration, depending on their thickness; they are available in 25-, 50- or 100-mm formats. Top-quality filters have an excellent filtration capability; they can trap up to 80% of the dust suspended in the air. Given this high performance level, these filters must be checked at least once a month during the cold months and, if necessary, cleaned. A dark or light greyish film will indicate the extent of the clogging. According to CAA-Quebec, only a brand-new filter can guarantee optimal air quality. Pleated filters cost from $15 upwards.

Top-of-the-range: HEPA filters
Are you one of those homeowners that wants optimal air quality? You will need a high-efficiency particulate air filter, also known as the HEPA filter. This device, which is independent of your furnace, is 95% effective. It is ideal for those of us who are sensitive to the irritants in the atmosphere or have chronic allergies. But, as you may have guessed, the HEPA filter can be quite expensive; it ranges from $250 to $300.

The future
Other technologies are being developed. One device that is becoming increasingly widespread is an air purifier that uses turbulence to collect even sub-micron dust particles with high efficiency.

There is a simple way to ensure that the air you are breathing is healthy. All you have to do is check your furnace filter regularly. When replacing it, opt for one of the slightly more expensive ones, as they offer superior efficiency. You may also opt for a filtration device that is entirely independent of your furnace. Your decision will depend on your requirements and the price you are willing to pay.

Prevention: the best way to control the quality of indoor air
Here are a few tips from the CMHC on ways to prevent dust and unwanted particles from accumulating in your home:
-  Avoid smoking indoors.
-  Reduce the number of surfaces that can collect dust, such open shelves,
   rugs and carpets, upholstered furniture, etc.
-  Reduce the entry of particle-laden outdoor air.
-  Use a good furnace filter.
-  Regular vacuum cleaning.

The above recommendations will help reduce the amount of dust visible in the house and reduce the load on your filter systems.