Summit Heating and AC Weighs in on Efficient Air Cleaning: How Air Purifiers Work


Air purifiers clean dust, pollen, mold spores, pet dander, and other small, particulate contaminants out of the air in your home. They can be a necessary addition to your home, as indoor air quality is often worse than outdoor. So, how do they work?

Types of Air Purifiers

There are two main types of air purifiers, standalone units, and whole house HVAC system purifiers. The latter ties directly into your home’s heating and air conditioning system and requires professional installation by a qualified contractor. The standalone units are just consumer electronic devices that merely need to be removed from the box, set up and turned on. Below, we will focus on these standalone units.

The Basics

In the simplest terms, air purifiers use internal fans to pull air in from the outside, where it is forced through a series of filters and then distributed back out into the surrounding air. The more air a given unit can process, and the faster it can do it, the larger a room the purifier is capable of cleaning.  As the air moves through the unit, it passes through the different filters included inside. First, let’sdiscuss how they work. The most important of these is the HEPA filter.

HEPA Filtration

HEPA, or high-efficiency particulate air filters, are the workhorse filters in most air purifiers. These use layers of material to catch and hold contaminant particles as the purifier forces air through them. There is no one HEPA design or set of materials. What’s consistent across all HEPA filters is that they capture 99.97% of all particles .3 microns in size or larger. To give you a sense of how small .3 microns is, 40 microns is the smallest object a human eye can see. White blood cells are 25 microns across. Red blood cells are eight microns. Large bacteria are two microns across. And HEPA filters can capture particles roughly six times smaller than that. You’re talking some of the smallest bacteria and viruses.

Activated Charcoal Filtration

Activated charcoal is an adsorption filter. Not absorption. Adsorption. This is a process where particles get stuck to the surface of a material. For a material to be an effective adsorption filter, it needs a lot of surface area, and this is where activated charcoal shines. It is riddled with networks of tiny pores that run throughout the material. This means a lot of surface area for particles, mostly smell-causing particles to adhere to. Activated charcoal is often added to air purifiers to help control bad smells in the air.

UV Light

Many air purifiers add a UV light source along the path air follows as it’s forced through the purifier. UV, or ultraviolet light, renders certain classes of microorganisms harmless and sterile. “It’s a useful addition to an air purifier because it boosts the unit’s ability to cut down on the bacterial pathogens that circulate throughout the air in our homes,” stated Bill Leech, a founder of Summit Heating andAir Conditioning.

Air Ionizers

This last piece of technology doesn’t filter the air inside your air purifier. Instead, it creates a weak electric field which produces negatively charged ions. These ions float around the room and latch onto dust and other neutrally-charged particles, giving them a negative charge. Then, because most room surfaces have a positive charge, the negatively charged dust particles are drawn to walls, floors, and other room surfaces, effectively getting pulled from the air. This is the only technology on the list with questionable usefulness. Some studies have found that air ionizers do very little to clean room air. And if they do work, they merely drop dust particles to the ground, where they can be stirred back up into the air by any given disturbance. And, because the process that generates ions also creates small amounts of ozone, which can be toxic, many people opt to turn the ionizer in their air purifier off.

Whole House Air Purifiers

Whole house purifiers, which are tied into your home’s heating and air conditioning system are a great choice if you want one unit to clean the air in your entire home. If this interests you, give the professionals at Summit Heating & AC a call. They can discuss your options and give you a free, written estimate.


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