How to choose the best air filter for your HVAC?

Are you confused about the air filter that you should buy for your home’s HVAC system? Are you looking for ways to choose the best air filter for your HVAC? Well, you have come to the right place for answers to these questions. Every HVAC unit is unique in its way, especially its air filter. We all know that an air filter is a crucial component of your HVAC as it makes the air you breathe clean and healthy. Therefore, you are required to be thorough while choosing the right filter. 

Factors to consider while choosing an air filter

There are some factors that you should consider before making your decision about which filter to buy. Let us have a look at the points that you need to keep in mind to choose the best air filter.

Size of filters

Various sizes of air filters are available in the market, but choosing the right one for your HVAC is a crucial thing. Even a little mistake in size can affect the efficiency and performance of your HVAC system. If the filter is bigger or smaller than the size required then the air will flow from around it or from the gaps in between. This will result in contaminated air passing through your HVAC system and impacting the air quality in your home. Following are some points that help in finding the right size filter for your HVAC system:

  1. Look for the label on the filter frame– The best way to find the right size for your air filter is to take out the current filter from its slot and check on its frame. Usually, the normal size of the filter is mentioned on the frame, which is different from the actual size. In case the actual size is not mentioned anywhere, it is better to measure the filter itself.
  2. Measure your old air filter– If you can’t find the filter size mentioned anywhere on the frame or if only the normal size of the filter is written there, the next step is to measure the filter yourself. It is important to know the actual size of the filter to get the right size. Take a measuring device and measure the actual length, width, and thickness of the current filter. Always remember to turn your AC off before taking out the filter slot for measurements.
  3. Measure your air intake– If in case you are not sure if the current filter of your HVAC system is of the right size, it is best to measure the inside edges of your filter slot or frame. Turn off your AC, take out the filter slot, and then measure the length, width, and thickness of the inside edges of the filter frame or slot. The actual size of the filter is usually a bit smaller than the size of the frame or slot and thus you will have to round down the measurements to the nearest whole number. But still, this method does not always produce the right results, so it is advised to use the above two methods for the right measurements.
  4. Contact the manufacturer– If all the above methods fail, you can contact the manufacturer directly and ask them about the right size of filter for your HVAC system, based on your system’s model number. They will give you the exact specifications of the filter that are made for your system.
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Types of filters

You can find various types of air filters for your HVAC system, which can be differentiated and described based on several factors like cost, efficiency, replacement schedule, etc. The two main factors to consider while choosing the right type of air filter for your system are:

  1. Low cost– Cost plays a crucial role in everything that you buy. Air filters are a major part of any HVAC system and they also have to be regularly replaced. Different types of filters have different prices, ranging from high to low. To keep things within budget, if you want to go for lower cost filters, here are your options:-
    • Washable or reusable filters: These are also known as electrostatic filters. These filters have lower costing and they are also long-lasting as they can be washed and used again. So, you are not required to change them very often, resulting in money-saving. These filters capture slightly bigger particles and also have a lower MERV rating. If not washed or cleaned regularly, these can worsen the air quality. 
    • Fibreglass filters: These filters have the lowest cost and are easy to replace. Fibreglass filters are not reusable or washable. These filters also have a lower MERV rating and they do not add much to cleaning the indoor air quality. 
  2. High performance– The other deciding factor for deciding the type of filter you need is its performance or efficiency. Go for filters with higher efficiency or performance, such as:-
    • Pleated filters: These filters are made of cotton or polyester and provide much better filtration for the contaminants in the air. They have a higher MERV value and help in cleaning up to 80% of the pollutants and dirt. These filters even filter out the smaller particles and their pleats provide greater surface area and density, resulting in higher performance and efficiency. These filters are required to be placed regularly.
    • HEPA filters: These filters have the highest MERV rating and are the best in performance. HEPA filters can filter out 99% of the pollutants from the air, including microparticles. But, these filters are not that good for residential HVAC systems as they are very expensive and their small pores may also restrict the airflow, resulting in damage to the HVAC system. 
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Filter change schedule

Image credit: Wikimedia Commons

Every type of air filter needs to be changed or replaced at a regular interval. If you fail to replace or change the air filter on time, it affects the efficiency of your HVAC system and your indoor air quality. But, how often you need to change your filter depends on some factors such as how often you use your HVAC system, the size of your home, and your home’s air quality. Some filters like fibreglass filters are required to be replaced every 30 days, while filters like pleated filters need to be changed every three months. So, before buying an air filter for your HVAC system, don’t forget to ask the manufacturers about the replacement schedule for each type of filter. 

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MERV ratings

MERV ratings define the efficiency of air filters in capturing the pollutants from the air inside your home. The higher the MERV rating, the better the efficiency of the air filter. Its range is from 1 to 20. The filters that are used for home systems namely fibreglass filters, pleated filters, UV lights filters, and electrostatic filters usually range between 1 to 15 or less. The HEPA filters have a MERV rating ranging between 16 to 20, but these filters are not ordinarily used in home HVAC systems. Look for air filters with a higher MERV rating while choosing an air filter for your system.

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There is no single air filter that fits every HVAC system. Getting the right filter is crucial and should be done carefully, after considering all the important factors. In case you are not able to identify what air filter will be best for your HVAC system and your home, contact an expert and follow their recommendations. Go for the filters that are the right size and work most efficiently in improving the air quality of your home. 

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    Perhaps, corrugated filters are the best option for the home when a good air purification is required. As for the MERV rate, for residential buildings a rating of 13 is enough.

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