Electronic Air Cleaners. Love Em Or Hate Em?

Sometimes called an electronic precipitator, these filters can be very effective in collecting the really fine particles traveling through your HVAC system. The problem with these air cleaners is that the more of those fine particles they collect the less efficient they become at collecting them.

I’m about to fill you with a bunch of non technical experience that I’ve had in installing, repairing and actually owning an electronic air cleaner. By the way I loved mine, because of how it was installed. More on that later.

I have had very few customer that would clean them often enough. When the plates in electronic air filters (EAC’s ) become coated with dust and other stuff, the openings between the plates are large enough to allow almost everything through the filter.

Oddly enough, I always disagreed with the way Honeywell directed home owners to clean their EAC’s. “Put them in the dishwasher.” Just never do that. The gap between the fins is critical to maintain a certain distance.

The prongs sticking up in most dishwashers would bend the aluminum fins and the air cleaner would be shorted out and not work or spark continuously driving the home owner completely nuts listening to that arcing.

And, it doesn’t take a very thick layer of dust to diminish the dust capturing capability of these air cleaners. The power head on one of these cleaners creates a very high voltage as you can witness in the video below. Turn up your sound.

How Do Electronic Air Cleaners Work?

As you can see in the video, these air cleaners can produce an lot of voltage. This voltage is distributed onto the cells in the air cleaner. Some of the aluminum plates that make up the cells are charged positive and some are charged negatively.

Remember your science about positive and negative particles?

Opposites attract.
These two types of electrical charges – positive and negative – are said to be opposite types of charge. And consistent with our fundamental principle of charge interaction, a positively charged object will attract a negatively charged object. … Objects with like charge repel each other.

https://www.quora.com/Why-do-positive-and-negative-attract

So as the particles of dust pass through the plates of the air cleaner they are charged one way and attracted to the opposite charged plate.

What Not To Do When Your Electronic Air Cleaner Fails

One service call I will never forget, I pulled out the filter and there was about three more of these laying down in the bottom of the duct.

The home owner evidently just kept adding new filters wondering where the previous ones had gone.

The frames on these filters are so weak that when they load up with debris they can easily get sucked out of the slot in the duct that hold them.

This type of filter isn’t even the correct dimension for an electronic filter can.

The next best thing done is to add a two inch pleated filter with a more substantial frame.

You may be purchasing a 20 X 20 X 2 inch filter but what you actually are getting is a filter that is 19.5 X 19.5 X 1.75 inches. It just won’t quite fit and when filters don’t just quite fit stuff gets by and into the fan and the coil and the supply duct work.

Next thing you know you need a serious duct cleaning.

So, What Should I Do When My EAC Fails?

You have two options.

  1. Have it repaired
  2. Replace the electronic cells with a proper media filter

Usually by the time an electronic filter fails it’s not worth repairing and replacing the cells with a disposable media is a really good option. Especially if you are tired of washing those cells all the time or ever.

The proper media filter would be available by looking up the model number of the electronic filter can and finding a media replacement. But here’s a simple guide if you are inclined to use Amazon. You would be throwing away those aluminum finned cells and installing a disposable filter.

  1. Honeywell FC100A1037 20 X 25 Merv 11
  2. Honeywell FC100A1029 16 x 25 Merv 11
  3. Honeywell FC100A1011 20 x 20  Merv 11

Above are a few of the more popular sizes. Below is a block of what Honeywell has available.

Filter SizeF100- MERV 11F200-MERV 13
16 X 20FC100A1003FC200E1003
16 X 25FC100A1029 FC200E1029
20 X 12.5FC100A1052N/A
20 X 20FC100A1011 FC200E1011
20 X 25FC100A1037FC200E1037
21.5 X 27.5FC100A1045N/A

Always check the nominal size versus the actual size and double check the fitment. These disposable filters may seem a little expensive, but most homes should get nearly a year out of one filter.

If you want some instruction on how to know when to replace these filters I wrote a complete article on the subject. Don’t throw them away too soon. And don’t wait too long to put in a new one. Read this.

How To Get The Best Out Of An Electronic Precipitator

The really cool thing about EAC’s is that they have a very low static pressure rating. Static pressure is like blowing through a straw and putting your finger over the end.

Before you put your finger over the end you have low static pressure. When you cover the end of the straw and blow, you have high static pressure.

The wrong filter in an HVAC system can create high static pressure. This is happen more and more as filters become more efficient. That’s why the filters above that I recommended are MERV 11.

Because, you don’t know what your static pressure is and by adding a high MERV rated filter you could be joining a club of those who kill their compressors or burn out a heat exchanger or melt an electric element.

So unless you are going to call a professional and have your static pressure tested then stick with the MERV 11.

Electronic filter come with a pre-filter to keep the big stuff out of the cells. If you’ve owned one then you have more than likely experienced the arcing that occurs when something gets stuck in between the plates

What if you had a quality filter before the EAC? Now lets say you added a second can that was media only, right before the electronic filter.

So you place this can in the duct prior to the electronic air cleaner that has the powered cells. This filter would be very effective and actually collect a good portion of the dust.

The electronic filter would then collect the finer stuff that gets through the media and your labor and time would drop considerably for cleaning the EAC.

Again it’s important to know the static pressure of this system. If you know your existing static pressure then you can add the static pressure of the EAC and the medial filter to know if you are in the safe zone.

Read this article if you want to know a little more of static pressure and how it effects the blood pressure of your HVAC system.

To Sum This All Up

Filtering is one of the most obscure functions of an HVAC system. Getting it done right is the one thing that will prolong the life and functionality of a gas furnace, air conditioner, or a heat pump.

So many things begin to slowly and almost unrecognizably go wrong when filters don’t do there job. Along with that and a lack of maintenance, the life of a system is shortened and expensive, just like the human body being captured by over consumption of drugs and alcohol or bad eating habits.

Chad Peterson

Chad Peterson is a veteran of the HVAC industry since 1977. "I like to explain heating and air conditioning problems in a way the average home owner can understand. "

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