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Like many products out there it’s a mixed bag. Depending on your priorities washable furnace filters can check a lot boxes – but they do have both positive and negative qualities. Let’s do a little research and lay it out.

Having a clean filter is a must, not matter what product you choose. Air filters are meant to protect both the mechanics of your furnace and the air quality of your home from airborne particles. Recommendations from manufacturers and HVAC experts is for homeowners to change (or with a washable filter, clean) their filters every two to three months. This is important for three reasons:

1. A dirty filter can harbour dust, mold spores, soot, bacteria, and allergens. And it all contributes to poor indoor air quality. This can lead to eye irritation, sneezing, dizziness, and worst of all can cause respiratory problems. People who have allergies or asthma are particularly susceptible. If you have pets, your home will have extra dirt and animal dander to contend with.

2. A dirty filter leads to extra ware and tear and breakdowns! When an appliance is clean and free of debris it works more efficiently and ultimately lasts longer. The filter will only hold so much dirt so if you don’t change it that means the dirt will penetrate further into your furnace causing blockages, overheating and damage.

3. A dirty filter makes your furnace work harder and use more energy. Over 50% of your home energy bills come from heating and cooling. When you air filter is clean, the fan motor runs efficiently, and you use less energy.

So now you know how important air filters are let’s talk about the different kinds on the market looking at type, costs and MERV rating (Minimum Efficiency Reporting Value). This is the standard measurement system for evaluating an air filter’s ability to trap air pollutants, going from 1-20. The higher the rating the better your home air quality should be.

Disposable Fiberglass HVAC Air Filters are probably what comes to mind when you think of a traditional furnace filter. Filters that are flat panels with fiberglass mesh over a cardboard framework. The mesh catches the dirt and debris as the air passes through. Fiberglass filters are cheap, costing you about $5 per filter. They are disposable and require you to change almost monthly. You can think of fibreglass filters as your base model with a MERV rating between 2-3.

Washable Mechanical HVAC Air Filters are made from woven polypropylene materials. They are electrostatically charged to filter out smaller dirt and particles. Electrostatic air filters work by using multiple layers of media which clean the air as it passes through the filter, they have a MERV rating of around 1-5.  Instead of throwing this filter out you can use water or a vacuum to remove the dirt and reuse. Washable filters are more expensive to buy averaging $30-100 and are more eco-friendly, lasting up to 10 years.
 

Disposable Pleated HVAC Air Filters are similar to their fibreglass cousins in that they can only be used once. However, they are built differently, made from layers of cotton or plastic fibers, and pleated to create more surface area to catch dirt. Pleated filters do a better job at removing larger particles and are also more expensive than a fibreglass filter. MERV rating sits at 7-12 and they can cost anywhere from $10-$40 depending on the quality.
 

HEPA HVAC Air Filters are in a class of their own and used in medical clinics, hospitals, and laboratories. HEPA stands for High Efficiency Particulate Air and remove at least 99.97% of all particles .03 microns or larger. These bad boys are available in both washable and disposable options. The majority of residential furnaces are not up for the HEPA task because the blower motor isn’t designed to work with such a thick filter. The MERV rating sits at 17-20. In most cases the highest rating that can work on a home furnace is MERV 13. To avoid spending a lot of money on a filter not designed for your furnace, it’s best to talk to a HVAC professional first, if you are looking for this level of air purification.

UV HVAC Air Filters do not rely on the material or style of filter but instead use the disinfecting power of UV or ultraviolet light to take away particles from the air, including viruses, bacteria and mold. UV filters are not washable or disposable because there is no physical filter – it is rather a supplement to another type of air filtration system.

Pros and Cons

Now that we have the basics in all things filters let’s get down to the nitty gritty of washable filters.

Pros

• Washable furnace filters are environmentally friendly, lasting for up to 10 years and possibly longer, reducing waste and energy.

• A washable filter can be cleaned as often as you like, improving your air quality without the guilt of a replacing with a new filter.

• When evaluated based on their lifetime cost washable filters are priced economically at $30-$100.

• Some washable air filters come with a warranty.

• Most hardware stores and Amazon carry these online and instore in both custom and standard sizes making them easy to purchase.

• Electrostatic air filter MERV ratings are higher than regular fiberglass filters.

• It’s a one and done for a long time, eliminating the need to buy replacement filters.

Cons

• Upfront cost is higher than purchasing disposable filters.

• They are not a substitute for a real HEPA filter.

• To work effectively and to protect your furnace, washable filters must be cleaned at least every 3 months. A thorough cleaning should take up to 15 minutes.

• You must wait before reinstalling and ensure they are 100% dry. If you are impatient and insert too soon the lingering dampness could attract mould and mildew.

• The reason washable electrostatic air filters work so well is because they are thicker and better at capturing smaller particles. This construction does not allow for as much free air flow and may cause your furnace to work harder.

• More than one source states “electrostatic air filters do not filter out large, heavy dust particulate matter that affects those suffering from allergies.” This could be in part due to the fact that over time the electrostatic filters can lose their efficiency as they get dirty.

The best way to clean your washable filter.

Washable filters are durable and can be cleaned with your vacuum first and then with water in your bathtub, kitchen sink or even outside with a garden hose. This type of filter can also be cleaned and wiped down with your regular household cleaner if you have some tough dirt or grease to remove. Rinse thoroughly and remove all water. If you’re concerned let the filter sit for an hour to prevent any moisture getting into your furnace or mold growing on the filter. The best part really is you get decide when and how often you wash your furnace filter.

What do we mean by electrostatic?

When air passes through the washable filter the dust particles are charged by the action of friction between the air taken into the furnace and the woven polypropylene. It is this material manufactured with electrostatic properties that creates the air filter media.

As particles in the air pass through the media, they are positively charged and quickly attach to the next several layers of the electrostatic filter. This is very similar to when your socks get static from walking across a carpet. It’s this electrostatic action that helps to filter out the contaminants and clean the air before your furnace pushes it back through the vent system of your home. This means less fine dust and dirt and should result in less dusting and vacuuming!

If you want to be cleaning the air 100% of the time, check your thermostat and put your FAN ON so it runs continuously rather than FAN AUTO where it will only be on when your furnace or air conditioning is running. 

One final tip

If in the end you opt for a washable filter, you’ll need to carefully measure before buying. Remember these filters are lot more expensive and are supposed to last you years. One important thing to know is the industry standard for disposable filters has for years been slightly smaller than the measurements listed by 1/4″ to 1/2″, making it a nominal size. In most cases this small difference doesn’t impact disposable filters BUT washable electrostatic furnace filters have a solid rigid metal or plastic frame. This makes the exact measurements more critical. Be sure to measure the height and width of your furnace’s duct opening. You can also consult with a local HVAC professional to help you select the right filter for your specific furnace model.

In the end it’s up to you
Different types of furnace filters work for different homes and family needs. If you live on a dusty road, have three cats and kids with allergies you should probably stick with a pleated disposable filter or up your game to a HEPA filter system. But if you are looking to try something new that has a better environmental footprint, the washable electrostatic filter may be up your alley.