Indoor Air Quality & Duct Cleaning

Your filters are very important in maintaining your HVAC system.

Filtering Particulate Matter

A build-up of contaminants on an indoor coil just 0.002” thick can reduce airflow by 9%.

Particulate matter comes in many sizes. Dust that you can see is only 1% of what’s actually in the air.
The remaining 99% is ultra-fine to coarse microscopic particulate, bio-aerosols, and volatile organic compounds that create real issues.

HVAC filters are MERV-rated based on their ability to remove different size particles.

Filtration starts with MERV-rating - Minimum Efficiency Reporting Value – a testing score on a scale of 1 to 16. We recommend using filters with a minimum of MERV 4. A MERV 16 filter has a 95% or greater efficiency. However, keep in mind, high efficiency filters load quicker and must be changed or cleaned more frequently. Most importantly, excessive pressure drop through the filter can result in degradation of system performance and possible failure.

Caption: Box and cartridge filters range from MERV 8 to 11. In addition to being more effective in capturing smaller particles, pleated box filters have a greater holding capacity due to increased surface area.

The Carrier Infinity Air Purifier is an actively-charged filtration system with an equivalent MERV-15 rating combined with a germicidal effect. This air purifier not only captures but kills airborne pathogens such as bacteria, viruses, and mold. It charges particles using an upstream grid and then collects them on a charged filtration media panel. Additionally, because of the higher voltage used in such systems, when biologicals are captured on the filter media fibers, they are mineralized, rendering them harmless carbons. It’s an effective easy-to-maintain option for concerns such as allergies and asthma, susceptibility to airborne germs, and sensitivity to molds, pollen, pets.

Eradicating Gases and Biologicals

The average home or office contains hundreds of different types of gases from sources such as internal combustion heating equipment, “off-gassing” from furnishings, carpeting, paint, cleaning products and deodorants, ozone and radon, and even “musty smell” from mold. Even at below permissible exposure levels, these gases cause sensitivity and irritation for many people.

Biologicals include fungus, mold spores, pollen, bacteria, and viruses. The indoor evaporator coil and return full of moisture, protected from ultra-violet sunlight, and creates a niche environment that would otherwise not exist outdoors. As biologicals propagate, it’s not uncommon for the number of spores in the indoor HVAC coil and return to exceed outdoor levels.

Filters are not enough for eliminating micro-organisms that attach to particulate matter to become airborne and are the source of many allergies. Filters collect dust and other matter that becomes nutrient for contaminants that then multiply and are carried downstream. In humid environments, mold can multiply and actually grow throughout a filter and live spores can be distributed throughout the airstream.

This applies also to volatile organic compounds and gases that are recognized by distinct odors and can become harmful at concentrated levels that occur with indoor air.

Removing germs, viruses, active bacteria and mold from an indoor environment requires eradication. This is done through means such UV light exposure and catalysts. A UV-C light over an evaporator coil and condensate pan for surface treatment is a very effective application for eliminating microbial organisms. The typical result is a return of the coil to an “as installed” condition including coil pressure drop and air flow. A UV-C light installed in a coil virtually eliminates the need for maintenance in cleaning the coil and reduces condensate drain blockage.

Other available systems can be installed in return ductwork that combine UV catalysts with filtration.

Ventilating with Fresh Outdoor Air

One-third of the indoor air should be changed every hour, not just filtered but exchanged for fresh outdoor air.

If this ventilation rate does not occur, indoor air in homes and buildings with modern, energy-efficient construction becomes stale and contaminated.

Modern homes are well insulated and sealed to conserve energy—trapping pollutants and increasing the concentration indoors. Moisture comes from cooking, washing clothes and dishes, showers, and even breathing. Construction materials off-gas (VOC) at a higher rate when exposed to higher temperatures and humidity.

Outdoor “fresh” air is often less polluted than indoor air and therefore “opening the window” will frequently improve indoor air quality by diluting indoor airborne contaminants. However, this is not always true. For example during pollen season, outdoor air can contain pollutants than make indoor air worse, not better. Also, you might not want to open leave windows open during February or August. Outdoor air must be “conditioned” to match temperature and humidity settings indoors.

Ventilation systems exchange and dilute contaminated indoor air with fresher outside air. Reduces concentrations of chemicals, fumes, carbon dioxide, and other contaminants.

An ERV allows fresh outside air to be brought inside and stale indoor air to be ventilated outside while keeping energy loss in the exchange to minimum. The incoming and outgoing airstreams do not mix, but the heat energy is transferred through a heat exchange core in the ventilator. An ERV also helps with preventing indoor humidity becoming too low in winter.