Air filters are something most homeowners or renters are familiar with. While most are disposable and inexpensive, there is one style of filter that may never need to be replaced. Electrostatic filters are washable, although not nearly as popular as traditional air filters. In this guide, we’re going to discuss these electrically charged filters to help you decide if they are the right choice for your home.
Electrostatic Filters Explained
You can walk into almost any hardware store or big-box retailer across the United States and purchase a pleated air filter. Electrostatic filters are not nearly as common, however, and something plenty of homeowners don’t realize exists.
These unique filters are often referred to as metal or washable air filters and rely on static electricity to trap particles traveling through the air. These filters are designed to create a charge through electrostatically enhanced fibers which turn them into a miniature ionizer to a degree without the fear of ozone like you’d find from an electrostatic precipitator or air cleaner.
Charged particles from the filter pass through another section that has an opposite charge, which causes them to become trapped in the air filters collector. Depending on the quality of the electrostatic filter, this process can be repeated multiple times before the air is cleansed and returned to your system.
Electrostatic Filters vs. Traditional Air Filters
When you understand what an electrostatic air filter is, you can compare them against traditional air or furnace filters. The first thing you’ll notice is they are constructed in a completely different fashion. Instead of having a frame made of thick cardboard, an electrostatic air filter’s frame is constructed from aluminum.
Aluminum is lightweight, but incredibly sturdy which helps these filters maintain their shape over years – not months. Both styles of filters are designed to protect your system from dust and dirt while keeping particles out of the air indoors, but their effectiveness varies in some very surprising ways.
When a traditional pleated filter begins to get dirty, it actually becomes more effective in a sense as particles will have a tougher time making their way through. Obviously, you’ll need to change and replace pleated filters before they become clogged, but they will still work to a degree until entirely blocked.
Leaving a dirty AC filter in too long may cause a strain on your HVAC system but pleated filters will still collect particles. On the other hand, electrostatic filters get weaker as the collector fills up, which means it’s less effective the dirtier it gets. These filters can also lose efficiency due to high humidity and certain aerosols.
By design, electrostatic filters are more durable and will last longer than a traditional pleated filter. They aren’t necessarily the best AC filters on the market; however, as it all comes down to the pros and cons in order to see if an electrostatic filter is the right choice for your home.
The Pros and Cons of Electrostatic Filters
With any type of product, you’ll find a few negatives to go along with the positives regardless of how great it is. While some of the benefits of using an electrostatic filter are fairly obvious, there are some significant drawbacks you should be aware of as well.
Pros of Electrostatic Air Filters
The biggest advantage of using an electrostatic filter is the fact they don’t need to be changed nearly as frequently. How often still depends on a variety of factors including the number of people and the type of activities in your home like smoking or pets, however.
You won’t have to make trips to the hardware store or order filters every few months for these cost-effective filters. Eco-friendly homeowners will appreciate the green nature of an electrostatic filter as well. Traditional filters end up in landfills, while the frame of an electrostatic filter can be recycled.
These durable filters are made to last and can hold up between 3 to 10 years or more on average. As with pleated air filters, quality matters and so does maintenance which is something we’ll touch on below.
Cons of Electrostatic Air Filters
Cleaning is often considered the biggest drawback of using an electrostatic filter. They don’t need to be thrown away, but they will have to be cleaned on a regular basis. It’s not as simple as shaking the dust off either, as you’ll need a bit of space outdoors to clean these charged AC/furnace filters.
Need a filter with a high MERV rating? That’s hard to come by with an electrostatic filter as they are not comparable to a high-end pleated filter or HEPA filter. These filters aren’t ideal in homes where people have allergies or respiratory issues and require a high degree of filtration indoors.
The high upfront cost of an electrostatic filter can be a negative initially, although it will quickly pay for itself. That includes the cost of replacement filters over time along with shipping charges if you purchase air filters online instead of locally.
Electrostatic Air Filter Ratings
The best way to tell the efficiency of an air filter is to look for a MERV rating. It’s the universal standard for air filters aside from MPR by 3M and FPR filters from Home Depot. Normally, the MERV rating scale for pleated filters runs from 1-16, and the higher the number on the filter, the more effective it is against fine particulates.
Unfortunately, electrostatic filters top out at the equivalent of around 7 MERV. That’s comparable to a filter that can block large particles including dust mites, pollen, and carpet fibers. A high-quality electrostatic filter can deal with dander and some aerosols as well. With that in mind, they are ineffective against things like cigarette smoke and fine particulates that can aggravate respiratory conditions.
Maintaining an Electrostatic Filter
If you own an electrostatic filter, you might not have to replace it for a decade but you will need to clean it periodically. According to most manufacturers, that’s at least once every 1-3 months depending on the conditions in your home. While you should always follow the manufacturer’s directions on cleaning these filters, the steps below will work for most electrostatic filters on the market today.
- Turn your system off and remove the electrostatic filter from the air handling unit. This was something we covered in-depth in our filter changing guide if you’re unsure of where filters are located on furnaces and AC units.
- Take the air filter outdoors to an open area where you have room to use a garden hose with a nozzle attachment. If you live in an apartment or condo, this can be challenging but electrostatic filters cannot be properly cleaned in a sink or bathtub indoors.
- Find the arrows on the frame which show the airflow direction. You want to spray an electrostatic filter from the opposite side of those arrows. This is called backwashing and clears contaminants from the fibers. Keep an eye on the pressure as well – too much could damage the media.
- When sufficiently cleaned, prop the filter up with the drain holes down. It could take between 30 minutes to an hour for the filter to dry. If you notice the filter still appears slightly dirty, perform Step 3 again until the filter is clean.
- When you are sure the filter is completely dry, replace it in the system and turn your HVAC unit back on.
In most cases, a simple hosing will be enough to clean an electrostatic filter. For tougher dirt, you can use a mild mixture of dishwashing liquid on both sides of the filter as well. You can use a vacuum attachment to remove surface dirt beforehand, but do not use any other cleaning agents on these filters.
Electrostatic Air Filter Cost
18” x 24” x 1”
24” x 24” x 1”
20” x 20” x 1”
20” x 25” x 1”
10” x 24” x 1”
16” x 24” x 2”
With traditional air filters, the rating and construction have a large impact on the final cost. The same rules apply to electrostatic air filters as well, although the MERV rating isn’t as big of a concern. In our research, we found that 90% of the electrostatic filters available on the market are the equivalent of a MERV 8 air filter.
The cost of a washable electrostatic filter largely depends on the size as most filters have multiple layers and “limited” lifetime guarantees as well. You can expect to pay between $35 to $70 for a charged filter that’s the standard 1-inch thickness. The price can double, however, with reusable electrostatic filters that are 2” or thicker.
Even with thicker filters, the price difference may be shocking once you crunch the numbers. A 6-pack of filters from Filtrete rated at MPR 600 which is the equivalent of a MERV 7 filter is priced around $50 per pack. That’s for a 16” x 25” x 1” filter, and comes out to $8.30 each.
A home that replaces a mid-grade pleated filter 6 times a year, or once every 2 months, will go through roughly $500 worth of mid-range filters over a 10-year period. By comparison, the same size electrostatic air filter from Electro Dust costs $99 and has a lifetime guarantee. It will pay for itself in only two years.
An electrostatic air filter may not be for everyone; they bring a variety of benefits to the table and can make disposable filters a thing of the past. While they are worth it from a financial standpoint, they are not ideal for homeowners that need a more effective air filter. If you are interested in a traditional fiberglass, pleated or high-end HEPA filter for your home, check out our guide to the best AC and furnace.
Q: Can you vacuum an electrostatic air filter?
A: Yes, and that’s a good way to keep dust, lint, and other larger particles off the filter between cleanings. Just use a vacuum or shop vac with a hose, but no brush as you don’t want to damage the electrostatically enhanced fibers.
Q: Are electrostatic filters noisy?
A: When properly installed no, but when they become dirty and large particles become trapped you may hear a popping or crackling sound. Cleaning the filter should solve the issue.
Q: Are Electrostatic filters used in furnaces?
A: Yes, you can use an electrostatic filter in an air conditioning unit or furnace.
Q: What is the difference between an Electrostatic air filter and Electrostatic Air Cleaner?
A: Electrostatic air cleaners and ionizers are powerful devices with charged plates that require electricity to work whereas an electrostatic filter does not require power.
Q: Is it safe to use a pressure washer to clean electrostatic filters?
A: While you can’t get enough pressure from an indoor faucet, using too much pressure could damage the filter. Don’t use a pressure washer, only use a garden hose with a nozzle to clean electrostatic filters.