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How to choose the right air filter

To continue operating efficiently, your home's heating and cooling system needs to be outfitted with proper filters. Air furnace filters, air conditioner filters, and HVAC (heating, ventilation, and air conditioning) filters all contribute to better system maintenance and cleaner indoor air. Here is a guide to help you select the right air filters for your needs.

How an air filter works

Whether intended for use in the furnace, the air conditioner, or an air purifier, air filters are crucial for keeping your HVAC system running smoothly. They work by trapping small particles as the air passes through them. This prevents dust, dust mites, smoke, pollen, mould spores, and pet dander from contaminating your system and hindering its efficiency. Quality air filters will save you on the cost of HVAC maintenance, repairs, and replacements. A more efficient system means lower heating and cooling costs as well.

Respiratory conditions like allergies and asthma can be triggered by particles circulating throughout your home, so reducing the volume of contaminants in the air can help bring relief. Some filters are even capable of trapping bacteria and viruses to reduce the spread of illness.

Features to take into account

After you have decided on an air filter type, there are a couple of other features to consider. One is the Minimum Efficiency Reporting Value (MERV) of your filter. MERV is a 1-20 rating system that represents how many particles the filter can capture. The higher the MERV rating, the smaller the particles it will filter out of the air.   

Here is a look at the effectiveness of filters with different ratings. 

  • MERV 1-4: Useful for filtering dust, pollen, and carpet fibres. 
  • MERV 5-8: Better filters that can also capture animal dander, mould spores, and dust mites. 
  • MERV 9-12: Highly effective filters capable of trapping auto emissions, lead dust, and even milled flour. 
  • MERV 13-16: Premium filters that can remove smoke, microscopic allergens, and even viruses and bacteria from indoor air. 

A MERV rating of at least 6 is generally recommended for use in the home. However, many homeowners opt for a rating from 8 to 13 to ensure that smaller particles are filtered out as well. Filters with MERV ratings between 14 and 20 are usually seen in hospitals and other clinical settings. 

Another type of filter to consider is a HEPA filter. HEPA stands for high-efficiency particulate air, and it refers to the fact that these filters are designed to trap the smallest and finest particles. HEPA filters may be a good choice for people who suffer from asthma, allergies, and other respiratory issues, but they can only be used in compatible systems.

The different sizes

Air filters come in a range of different sizes, so you need to be careful to choose the correct size for your HVAC system. A proper fit will ensure that the filter works as it should. You can find the right size by taking a look at your current filter, which will have the measurements printed on the frame. The numbers shown are the length, width, and depth of the filter, in inches. 

Some of the most common filter sizes are: 

  • 16" x 20" x 1" 
  • 16" x 25" x 1" 
  • 20" x 20" x 1" 
  • 20" x 25" x 1" 
  • 20" x 25" x 5" 

Air filter care and maintenance

Air filters will become dirty over time, potentially hampering your HVAC efficiency and lowering your indoor air quality. Here are a few tips to keep them properly maintained and working as they should: 

  • Wash or replace your air filter as often as is recommended by the manufacturer. 
  • Most air filters need to be changed or cleaned monthly, but some may last up to 90 days. 
  • Consult the packaging for information and guidance on your specific model. 
  • Consider marking your calendar or setting a reminder for filter changes. 
  • If you live with pets or own a larger home, you may need to change your filter more often. 

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