Should I Consider an Air Cleaner for my HVAC System?
According to the US Environmental Protection Agency (EPA) article titled “Guide to Air Cleaners in the Home”; “Indoor air pollution is among the top five environmental health risks.”
Pollutants are harmful to everyone, especially those who suffer from asthma, allergies or lung disease such as COPD/emphysema.
Particles commonly found in residential air include mold, dust mites, pet dander, microplastics, pollen, bacteria & viruses.
The EPA lists gaseous pollutants known as volatile organic compounds or “VOC’s”. VOCs can leach from flooring, furniture, chemicals from air fresheners, cleaning agents, pesticides and tobacco smoke where smokers are in the household making indoor air pollution a serious concern.
Could a whole-home air purifier be the answer?
What you should know when looking into air purifiers for central HVAC systems:
- What is an HVAC Air Cleaner?
- Residential air purifier types
- Pros vs Cons
- Indoor air purifier cost
- Is it right for you & your family?
- What else you can do to improve the air quality in your home
Central Air Purifiers – Types
Air purifiers also referred to as air cleaners; are designed specifically to remove pollutants and allergens by filtering the air in your home.
HVAC air purifiers like the ones used by Air Dynamics are installed in the return-air ductwork immediately before the air handler or furnace. Some filters are replaceable while others can easily be washed. These units do not use electricity; rather they filter pollutants from the air flowing through them while the blower fan is running.
Type 1: Media Air Purifiers
Also called mechanical air cleaners, these units use filters that not only last longer than standard furnace/air handler filters; but are made thicker and denser in order to better trap smaller particles than a standard filter would.
Most media air purifier filters have a MERV rating or Minimum Efficiency Reporting Value. The higher the MERV rating, the more efficient the unit will be when filtering smaller particles from the air.
Some homeowners want cleaner air, so they buy an HVAC filter based only on it’s high “MERV rating.” Here’s the problem: Some filters that have a high MERV rating can actually drop the air pressure in your duct system. This drop can increase energy consumption and cause damage to your HVAC system.
If the filter is thin and the MERV rating is high, it actually reduces airflow into the duct system. Low airflow = wasted energy and ultimately more work on your HVAC system overall.
Knowing this, it is important to select the right kind of MERV filter for your unit. A thicker filter (4-5 inches) will have more surface area and therefore allow more clean air to easily pass through. Thick filters have other benefits as well including:
- Higher dust-holding capability (meaning it can catch more particles without blocking airflow)
- Longer life ( on average most pleated 4-in and 5-in-deep media filters will last between 6 months to a year between changes)
The three types of media air filters are:
1). High-Efficiency Particulate Air Filters – HEPA filters
HEPA filters are recognized by OSHA and the EPA as one of your best lines of defense when it comes to removing airborne particles. HEPA products filter air at a very fine level, these filters do exceptionally well at blocking elements that are 0.3 microns or larger. This type of filter has been well tested and proven to catch 99.97 percent of all particles. HEPA filters typically have MERV ratings ranging from 17-21.
2). Activated charcoal/carbon filters
Remove odor-causing particles from the air. These filters are used in combination with a standard media filter to remove both particles and odors. They are an excellent choice for homes where odors from pets and cooking are of issue. The carbon molecules in these filters have a tremendous surface area. Each pound of activated carbon has a surface area of +/- 100 acres for gas to either pass through and be absorbed or bond with.
If your home’s odors are caused by other contaminants such as mold or mildew, simply filtering out the odor isn’t the right solution. Locating the cause of the mold and remedying it immediately is critical to maintaining a healthy home.
3). Charged media filters
The filters are given an electrostatic charge in the factory. Small particles are then attracted to the static charge similar to that of a sweater or towel clinging to items when removed from a hot dryer. In addition to their particle capturing efficiencies, filters made with charged media can allow for more energy-efficient operation of your
Pros of Media Air Cleaners:
The upside to media-type air purifiers is that they effectively remove more than 99.9% of pollutants and allergens from the air inside your home. Typically these units are more affordable to install and offer a selection of cost-effective filter replacement options.
Cons of Media Air Cleaners:
While most HVAC systems will allow you to turn the fan on even if you are not heating or cooling your home, media air cleaners can only remove pollutants that pass through them. Which, means that these air cleaners can only remove air pollution when your blower fan is actively running. This necessary action will produce slightly higher electricity costs but cost less to run then a stand-alone air purifier at years end.
Type 2: PCO Media Air Purifiers (Photocatalytic Oxidation)
Photo Catalytic Oxidation (PCO)
is an advanced process by which volatile organic compounds (VOCs), bacteria, mold & fungus are destroyed by incorporating photon and ultraviolet (UV) energy activating a catalyst which creates
Pros and cons of PCO air purifiers:
This technology has been proven effective and is frequently used in healthcare settings and food processing for air cleaning. A PCO combination or hybrid air cleaner is the most effective option available. A PCO filter does not hinder airflow, thus effectively saving your HVAC system from unnecessary strain. The downside to a PCO or PCO combination filter is the higher initial unit cost of the air cleaner and the electricity cost monthly to run it.
Type 3: Electronic Air Cleaners (EACs)
Most EACs include two types of filtration. These units are also typically referred to as ionic and electrostatic air cleaners. A pre-filter catches large particles. Then, the tiny remaining particles in the air are charged with electricity. This charge attracts them towards collector plates that have an opposite charge, sort of like magnets. This works exceptionally well at removing the offending particles from the air. In some cases, the electrical charge will even effectively destroy that virus or bacteria. Further preventing the spread of these nasty particles in your home leaving you with cleaner fresher air. As an added bonus, these filters can be easily cleaned in the dishwasher if needed! Keep in mind however that they should always be air-dried after.
Pros and Cons of Electronic Air Cleaners:
The filters in electronic air purifiers are washable; making them easier to maintain and reducing landfill waste. Simply wash off the filter every 6-12 months to keep it performing as designed.
The downside, as with mechanical air purifiers, electronic models only filter the air when the HVAC system is running.
Type 4: Combination Air Purifiers
Some whole-house air cleaners offered today combine the technologies discussed here (media filters, electronic charging & UV light). The cost goes up for these units, but they have the advantage of removing small and large particles in addition to in-home odors.
HVAC Indoor Air Purifier Cost
This table summarizes the various costs for the types of air cleaners discussed above.
When considering the purchase of a new Air Cleaner it is important to note that both size and features are main factors in determining unit costs. One of our highly qualified techs at Air Dynamics can help you determine what unit size/type would best suit your personal needs.
Are Add-on Air Purifiers for HVAC Systems Worth the Cost?
In summary, a central air purifier can be part of a broader solution to indoor air pollutants in your home for those who are more sensitive to indoor pollutants. However, If you’re not regularly experiencing breathing or allergy problems, adding more equipment to your HVAC system probably isn’t the most cost-effective response to indoor air pollution for you.
Here is a breakdown of the four types and they’re recommended uses:
- Media air cleaners: A good fit for homes with healthy inhabitants where less than 3 pets reside. A high-MERV or HEPA filter is highly recommended for homes in dry, dusty climates.
- Media plus PCO air cleaners: These cleaners have the same benefits as media air cleaners, but are especially useful where household odors are also a problem.
- Electronic air cleaners: Recommended for homeowners that don’t want the cost associated with regular filter replacement. Some studies show that electronic air filters will also kill viruses and bacteria more effectively. This is particularly useful in homes with small children and/or elderly who are more susceptible to illness.
- Combination units: These advanced air purifiers use multiple means of cleaning your household air. They are ideal for homes where members have known breathing issues such as asthma, allergies & COPD.
If you’re really interested in keeping your air clean, Air Dynamics suggests you consider having an air cleaner/purifier installed in your air ducts. Air cleaners, which have a thick media filter, can trap small particles, like pet dander and mold, without impeding airflow the way a thin, pleated air filter would.
Healthy indoor air is achieved through a range of practices;
Installing an air purifier is one of them.
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