Do Electrostatic Air Filters Work?  The Pros and Cons of Washable Furnace Filters.

Do Electrostatic Air Filters Work? The Pros and Cons of Washable Furnace Filters.

There are many types of air filters on the market these days, but which one is best?  We are often asked the question, do electrostatic air filters work?  The real answer is, it depends.  Electrostatic air filters are washable furnace filters that can be very useful for certain uses, but whether or not they should be used in your house is a much broader question.  If someone in your home suffers from asthma or severe allergies then the answer will likely change.  As a general rule, electrostatic air filters cannot even come close to the filtration power of a high quality anti-allergen filter from 3M or Honeywell, but that doesn’t mean you should rule them out altogether.  Those of you who read our articles regularly, know that we are a small, U.S. Veteran-Owned HVAC company in Southern California, and pride ourselves in giving people honest, straight answers to their questions.  In this article, we will discuss what an electrostatic air filter is, how it works, the pros and cons of using one and whether or not washable furnace filters would work for your home.

What is an Electrostatic Air Filter and How Does It Work?

Electrostatic air filters are washable air filters that theoretically never need to be replaced.  I say ‘theoretically’ because the idea that something that is subjected to dirt and debris regularly will also work indefinitely, seems too good to be true.

The idea is that instead of replacing your electrostatic air filter at regular intervals like you would a conventional air filter, you take them out back and wash them off with a hose about once a month.  This is a handy trick if you are sick of spending money on conventional air filters, but do electrostatic air filters work?  They do work, but the question is do they work as well as a conventional air filter?

do electrostatic air filters work - how to clean an electrostatic air filter

For more information on conventional air filters and how often you should change them, take a look at: Air Conditioning Filter Change – How Often Should I Do It?

How Do Electrostatic Air Filters Work?

These washable furnace filters work by having multiple layers of vented metal which the air passes through.  As the air passes through the first layer of filtration, the air molecules are positively charged by the friction between the air and the filter.  The now positively charged air molecules attach themselves to the next few layers as they pass through the rest of the filter.  Think about it as working kind of like walking across the carpet with your socks on and then touching a door knob – the process of walking across the carpet charges you with static electricity which is then released when you touch a grounded surface like a door knob.  Only instead of your socks scooting across a carpet, it is the air scooting across your air filter that creates a charge and traps dust particles in the air filter.  For more information on electrostatics, try this short vintage physics video – it’s worth a look: Electrostatics – How Electrostatic Air Filters Filter Air.

new washable furnace filterThe Pros of Electrostatic Air Filters

One of the most attractive parts of washable air filters is the fact that you never have to buy a new one.  This is definitely a plus, I mean who wants to buy a new air filter every few months?  Even if you opt for the cheaper air filters that run you 50 cents each (which I do not recommend), you still have to go through the hassle of buying them and replacing them on a regular basis and who wants to deal with that?

The other appealing part about using electrostatic air filters is the price.  If you are buying high quality air filters then you may be spending $15 every few months which adds up to around $60 each and every year.  Now even though this might not break the bank, it can add up over time.  Washable furnace filters cost around $50 to $60 each but never have to be replaced, meaning that they pay for themselves in the first year of their use.  You can’t argue with the cost of these filters, so it may be an option to keep in mind.

The Cons of Electrostatic Air Filters

I have to say that the cons of an electrostatic air filter far outweigh the pros, in my opinion.  There are several problems with a washable air filter, ranging from how effectively they filter your air to how often they have to be washed.  Some of these problems are a matter of preference, but some can’t be argued with and should be kept in mind before making your decision:

washable air filter pack - do electrostatic air filters workElectrostatic air filters can only filter so much.  One of the problems with electrostatic filtration is that it relies on static electricity to operate.  What I mean by this is that static electricity is powerful enough to filter small, lighter dust particles out of the air but what about larger dust and dirt particles?  Or mold spores?  Unfortunately, this is one of the areas that electrostatic filtration falls short in.  An electrostatic air filter will never be able to filter as well as a high quality HEPA filter or even a moderate 1200 MPR filter (micro particle performance rating).  These filters are designed to filter out everything down to a certain specification size and are good at what they do.  If you have someone in your house who suffers from asthma or bad allergies, then I’d definitely recommend you avoid washable furnace filters and instead opt for a high-filtration replaceable filter with at least a 1400 MPR.  For more information on this, take a look at: How to Reduce Asthma Symptoms and How Your Air Conditioner Can Help.

Other problems with electrostatic air filters include:

  • An additional problem that you run into with inadequately filtered air is that your air conditioning coils get caked with any dust and debris that is not filtered out.  Aside from this stuff polluting your air, it provides an organic substrate for mold and mildew to grow in over time.  If enough of it collects, then you have a perfect recipe for what is called Dirty Sock Syndrome, a situation where your air conditioner starts to make your house smell like a gym or locker room.  It isn’t pleasant.
  • do electrostatic air filters work - new filterWashable air filters also take time to clean.  Unfortunately, it isn’t just a matter of spraying them down with the hose as they’d like you to believe.  That would make the outside layer clean, but these filters have between eight and ten layers to them.  You actually have to disassemble them and clean each layer separately to properly use them.  This takes about 20 minutes every month or so to do, depending on how much dust is in your area.
  • Electrostatic air filters also block air flow more than conventional air filters.  Although this may not seem like a big deal, it is to your HVAC system.  If air flow is restricted by 50%, then your air conditioner has to work twice as hard to do the same amount of cooling.  It is true that all air filters restrict air flow to some extent, but electrostatic air filters block more than any other type of air filter.  In fact, we often get maintenance calls for units that use them.  If your air conditioner is running twice as much, its components will wear out quicker.
  • Because this type of air filter uses static electricity to operate, any particles that make it through the filter are now likely to stick to the inside of your duct work which can promote mold growth and possibly force you to have your air ducts cleaned.  What you will also notice with time is that black dust will start to accumulate around the walls of your house – this dust is difficult to clean sometimes because it is ionically charged and wants to stick to a surface (which is how an electrostatic air filter works).

Just food for thought before investing in a washable air filter.  For information on how to prevent mold and whether or not you need to have your air ducts cleaned, take a look at these helpful articles:

Should I Have My Air Ducts Cleaned? 

How Do You Prevent Mold?

Save Money on Your New Air Conditioner or Furnace by Watching This Short Video

If you’re in the market for a new air conditioner or furnace, you can save some serious money by being properly educated on the process, as well as avoid the tricks and traps of predatory contractors.  Watch this short video to find out more:

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Do Electrostatic Air Filters Work?

It depends on what you mean by ‘work.’  They do remove some dust particles from your air, but overall I do not recommend electrostatic air filters for home use.  Electrostatic air filters are an interesting technology but they just won’t work as well as a 3M 1600 MPR and they never will.  The nasty stuff that is in your air needs to be removed for the health of you, your family and your air conditioner.  A disposable filter allows you to do this, then throw this nastiness into the garbage where it belongs.  In the end, although they are a great idea in principle they just won’t filter your air as well as a conventional air filter will.  If you add in the hassle of having to spend 20 minutes a month washing it, then you just aren’t coming out ahead in the long run.  For more information on washable furnace filters and other related topics, visit our air conditioning blog.  If something a contractor is telling you doesn’t seem quite right, consider using our Online Air Conditioning Consultation Service – we’d be happy to answer any questions that you might have.

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Timothy Kautz
About the author
Tim K.

The University of Virginia - 2005 / The Wharton School of Finance - 2016 / U.S. Naval Aviator 2005-2015. At All Systems Mechanical air conditioning and heating, we believe that the experience our clients have is every bit as important as the products they receive. Simply put, our results speak for themselves, and we'd be happy to help. If you're in the market for a new AC or furnace, make sure that you get a fair price! Try our online calculator; click the tab on the top of this page for more information.

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