Overview
Indoor Air Quality (IAQ) is a current buzzword in the Heating, Ventilation and Air Conditioning (HVAC) Industry.

We hear about Legionnaire's disease outbreaks traced to the air conditioning system. Buildings are highlighted on the news as making their tenants sick and it's referred to as sick building syndrome. Individual homes are linked to increases in allergies and asthma. Can it happen to your home and what can you do to prevent it or correct it if you are already the proud owner of a house that is making you sick?

The ever-increasing cases of sick building syndrome are due to the way houses and buildings are constructed to conserve energy. Stop air movement in and out of the home and you reduce the energy required to heat and cool the house. After you seal the house up, central cooling and heating systems maintain livable temperatures and humidity levels within the home by re-circulation of the same air and pollutants day after day. Dust, bacteria, viruses, mold, fungus, mildew and gases circulate through the building. The dust can come from skin, hair, clothes or just come off shoes when we walk in and out. The mildew, fungus and molds can come in along with the dust or we can grow our own in the HVAC system. The gases are volatile organic compounds that are given off by dyes, paints, varnishes and adhesives used in modern building materials. The best example of gases is that burning eye sensation we get after new carpet is installed. So let's look at Filtering The Dust, Killing the Mildew, Molds, Fungus, Bacteria, and Viruses and Ventilating the Volatile Gases in an attempt to breathe easier.

Filtering the Air We Breathe

The most important step in filter improvement is to make sure that all the air that goes through the electric air handler or gas furnace is filtered. If your HVAC system is pulling air through cracks in the duct system or return air chase, it pulls the contaminates along with it. Have your service technician check to verify that all the return air to a system is pulled through the filter system. This is a good time for your service technician to verify that the filter system is sized large enough for proper operation of the system.

Filters come in different efficiencies that are measured in the percentage of arrestance of particles. Simply stated, what amount and size of particles do they stop? The higher the percentage, the smaller the particle the filter will stop. The other factor that must be considered is the resistance to air flow, or will this super filter let enough air through to allow my system to function properly?

Fiberglass - these are the most inexpensive filters that you can buy. Most people refer to them as the filter you can see through. They stop 15 % of the largest particles in the air. Replace monthly.

Pleated Paper - these filters look like a paper version of drapery pleats and stop up to 45% of the particles in the air. This type filter is the easiest upgrade for the money spent. These filters come in the same size as a fiberglass filter and are available at most hardware/home improvement stores. This type of filter gives the greatest degree of improvement for the money spent. Replace every 1 to 3 months.

Media Filter - these filters are up to 4 inches thick and come in limited sizes, though the size selection is increasing. Rated at 90 to 95 % efficiency, these filters are changed 2 to 3 times a year. Media filters require a special frame to be mounted in the wall or mounted directly to the furnace or air handler. There are some media filters that come with special adapters that allow them to be mounted in a standard filter frame that has 4 inches of clearance behind it.

Electrostatic filters - As an upgrade to Fiberglass filters, these are made up of layers of synthetic material that generate an electrical charge to attract dust particles. Electrostatic filters come with guarantees from five years to life. There have been problems due to high restriction of airflow across the filter. This reduction of airflow can greatly reduce the system capacity and efficiency. A new generation of these filters is now coming to market that promises less restriction to airflow. Clean at intervals of between 1 to 4 weeks.

Electronic Air Filters - this is the premiere filter system on the market today. An electrostatic grid is powered when the AC or heat comes on and attracts particles to it. The grid is cleaned as needed with a water hose or in the dishwasher. This is the most efficient filter system available. This type of filter normally fits the same space as a Fiberglass filter, but does require modification to the ductwork and wiring to be installed in your air conditioning system.

Some contractors pre-filter either the media or the electronic filter with a pleated paper filter and move their cleaning or replacement to a yearly schedule. The main idea regardless of the type of filter you choose is to filter all the air you circulate in your house and to remove as much dust and other particles as needed to breathe comfortably. One benefit of the high efficiency filters is a reduction in the need to dust the furniture.

Killing the Mildew, Molds, Fungus, Bacteria, and Viruses

One of the ways our air conditioning system keeps us comfortable is by removing the water vapor (humidity) from the air. As the AC system condenses moisture from the air, a drain is supposed to take this moisture out of the system. What really happens is that some of this water splashes on the interior insulation and some of it is left standing in the bottom of the pan that is not designed or installed to get it completely out of the system. So, now, we have moisture ready to support the growth of assorted micro-organisms that will cause a variety of respiratory problems.

The simplest treatment is to keep drain lines clear and to have a positive drainage on the coil.

Pan tablets and drain pads are available that release chemicals into the condensed water and kills the pathogens. These tablets or pads must be physically placed in the evaporator drain pan on a 1 to 6 month schedule.

UV lights are the newest tool to be used to improve indoor air quality. Similar to the lights that barbers, dentists, and doctors use to sterilize their instruments, these lights are designed to not only kill what's growing in the drain pan, but also what is growing on the coil surface or on the interior insulation. These lights will kill the source of numerous allergens that people did not know existed. The light shines on the inside of the AC, in front of the coil, 24 hours a day. Even if a new bulb is required every year, the UV light combined with a good filter system will greatly improve the quality of air in either a home or business.

Even older air conditioning units can usually be retrofitted with UV lights.

Ventilating Gases

As home construction has produced tighter homes, reaction to gases released from building materials has increased. The trick is to bring in fresh air without having to heat, cool or dehumidify it. This can be accomplished in several ways and must be routed through the filter system.

Heat Exchangers - exhaust air is pushed through a tubular heat exchanger as fresh air is pulled in around the outside of the tubes, allowing the air to exchange heat. The exchanger does not bring hot air down to room temperature or cold air up to room temperature but does reduce the temperature difference and the energy needed to bring it to the desired temperature. This solution guarantees fresh air will enter the house and stale air will be exhausted along with the toxic gases.

Desiccant Wheels - similar to heat exchangers but use a rotating wheel to remove humidity from the incoming air and add it to the exhausted air. Desiccant wheels will be used were humidity is the greater problem; heat exchangers will be used where low winter temperatures are the greatest problem.

Conclusion

In conclusion, these various methods to improve air quality can be built into a new or replacement system at the time of installation to achieve the best-cost savings. Any of these improvements can also be added to an existing system. You may find relief with just improving your filter system or with a filter and an ultraviolet light. However you mix and match to achieve breathable air, your licensed HVAC contractor can provide you with the needed expertise and quality equipment to accomplish the job.

Questions?

Please direct any questions to info@vaheatingandair.com. We look forward to hearing from you!