Furnace Filters

Green Home Guide: Replacing Your Furnace Filter

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TORONTO – For GTA residents who thought the region’s chilly winters couldn’t get any worse than the “polar vortex” of 2014, a chilly surprise may be in store – just three weeks into 2015, the City of Toronto has already issued more than a half-dozen “extreme cold weather” alerts.

For most homeowners, that means the furnace is already working overtime to keep things warm – and will probably get a substantial workout before the spring’s warmer temperatures arrive.

Just like most major home appliances, furnaces require upkeep and maintenance to perform at peak efficiency. Fortunately, one of the most crucial furnace maintenance tasks is also a relatively simple one you can take care of yourself: regularly replacing or cleaning the air filter.

The function of filters

In order to effectively do their job, furnaces must be able to draw in cool air with the help of a “cold-air return” mechanism – one of several key components that can be found in almost all home heating systems.

In modern furnaces, the first thing returned cool air meets is a purpose-built filter designed to keep everyday air pollutants – such as dust, smoke and pet dander – away from other components such as the fan motor.

When changed regularly, however, furnace filters can have the added benefit of improving air quality throughout the home. This is especially true for more expensive filters that, in addition to lasting longer before needing to be replaced, are engineered to more effectively catch tiny household particles such as bacteria, pollen, and mold spores.

Why – and how often – should furnace filters be changed?

Air particles caught by a furnace filter will accumulate on its surface over time, eventually reaching a point at which they may restrict air flow into the furnace itself – ultimately affecting the air pressure in the home and forcing the furnace to work harder. Constricted air flow can also hamper the furnace’s ability to regulate its own temperature, causing a possible fire hazard.

While all filters must be replaced eventually, a single filter’s lifespan depends on its type – and can vary from one to two months  – or even three months, according to Filtrete – for basic fiberglass or paper models, to up to five years for reusable filters that can be periodically cleaned. It is always a good idea to check the packaging for specific instructions on when to change.

Shopping for replacement filters

More than ever, furnace filter manufacturers are working to satisfy Canadian homeowners’ increased focus on efficiency, comfort, and value. Fortunately for consumers, that means that a strong selection of materials and technologies are likely to be available at your local hardware store.

With that in mind, here is a quick list of the most popular filter types currently available:

  • Disposable filters, made from fiberglass or paper, are generally the cheapest to purchase. They also have the shortest lifespan, and need to be checked regularly (see above). Some disposable filters feature a pleated design, allowing for a larger surface area that can increase the timeframe between changes.
  • Reusable filters are made from washable materials and, if cleaned regularly, can be used for several years – it is recommended that buyers refer to packaging and instructions for specific lifespan.
  • Both disposable and reusable filters are available in models that feature self-charging electrostatic These tend to be much more effective at capturing smaller particles within the returned air.

When shopping for new filters, keep an eye on objective product scores – such as the Minimum Efficiency Reporting Value (MERV) rating – that measure a filter’s effectiveness in capturing different sizes of air pollutants. Different furnace models also require different sizes of filters, so check yours before you head out to the store.

Changing the filter:

If you feel confident changing your own filter at home, the good news is that it’s a relatively quick and easy chore – but you should always be sure to follow safety precautions outlined in your  furnace’s instructions. Online video tutorials like this one may be helpful in getting started.

Photo via Collin Anderson on Flickr.

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