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Air Quality Advice

Indoor Air Quality

There is no question about it, Indoor Air Quality (IAQ) is one of the most underappreciated and debated topics with it comes to our industry.  Opinions vary so widely because over the years technicians have seen everything that the wrong kind of air filter can do to a home’s HVAC system: from coils, motors, and blowers too clogged by weak filters to burnt-out motors and controls because of too-restrictive filters. HVAC air filters are important for removing contaminants from the air to improve your home’s air quality. The better the air quality, the better your HVAC system runs and the better your family’s health.

Air filters are rated according to their Minimum Efficiency Reporting Value (MERV). Created by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), it’s a porousness scale that goes from 1 to 16, with most home air filters ranging from 4 to 13 MERV. The higher the MERV, the more contaminants that are removed from the air.

Air filters are made from different materials of different thicknesses and sizes.  All of these factors can effect their rating.  Here is a list of the general catagories of MERV ratings.

  1. Spun fiberglass filters (MERV 1-4): Cheap and disposable, these filters will catch 80% of particles 50 microns and larger, and snag 25 percent of the particles in the 3 to 10 micron range. Many manufacturers recommend these filters as minimum protection just from dust and dirt building on fan motors, heat exchangers, and other surfaces. They filter out large particles to protect the furnace components, provide maximum airflow but don’t filter the tiny harmful contaminants that affect your health.
  2. Disposable pleated paper or polyester filters (5 to 8 MERV ): These median-sized filters trap 80 to 95 percent of the particles 5 microns and larger. They cost four times more than the spun fiberglass filters but do a better filtering job.
  3. Electrostatic filters (2 to 10 MERV): These use self-charging fibers to attract particulates out of the air. Disposable pleated versions run about $10 in standard sizes (example: 16″ x 25″ x 1″). Washable versions (rated 4 to 10 MERV, usually not pleated) sound like a great way to save money but quality varies with cost. Better quality ones can last up to 8 years. These filters must dry completely after washing in order to avoid mildew or mold growth so a handy trick is to buy two and rotate them out for cleaning.
  4. Disposable pleated high MERV filters (11 to 13 MERV): High-efficiency filters can trap 0.3 micron particles like bacteria and some viruses. Two to five inch thick versions of these filters fit in box-like housings mounted onto the air handler and can last up to one year. Periodic changes to the filter design can add to the price.
  5. High-efficiency particulate arrestance (HEPA) filters: These are the true high end of filtration and are  able to filter out 0.3 micron particles. HEPA filters drastically restrict airflow and should only be matched to a compatible system.

What about the cost?

Will you save money by going with a more efficient filter?  This really depends on where you live and how you use your system. Experts have estimated that the average cost reduction derived from using a high efficiency filter is approximately 10%. This cost savings includes the reduction in fuel consumed by your HVAC system, and reduced repair and maintenance costs.

What are some problems and solutions you may encounter?

We spend 90% of our lives indoors and the average person inhales over 3,500 gallons of air each day. Don’t you think it is time to pay more attention to the air we breath? Some issues created by poor IAQ are:

  • Allergies
  • Fatigue
  • Asthma
  • Irritated Skin
  • Headaches
  • Discomfort
  • Lung Irritation
  • Home Damage
  • Higher Energy Costs

Unfortunately, there is no easy “cure-all” solutions (despite what the Sharper Image may tell you). Indoor air quality often requires multiple solutions for multiple problems. Have Harker Heating & Cooling design a system that suits your needs. In the meantime, here are some things you can do to help with your home’s indoor air quality issues:

Problem #1


  • Odors – emitted from litter boxes, trash cans, dirty hampers, cooking, smoking, paints and solvents.
  • Gases and vapors – emitted from new carpeting, building materials, cleaning supplies, candles, pesticides, personal care products, glues and adhesives.
  • Stale and stuffy air – a result of today’s energy efficient “tight” building techniques.

Problem: Poor Ventilation

Primary Solution: Install a Energy Recovery Ventilator

Things you can do to help:

  • Store volatile chemicals and cleaning products outside the home.
  • Keep litter boxes away from heating and cooling system vents.
  • Change your furnace filter according to manufacturer’s recommendations.
  • Have your fireplace and/or wood stove periodically cleaned and inspected.
  • Clean dryer vents on a regular basis.
  • Open windows and doors, as weather permits, to replace indoor air with fresher, outdoor air.
  • Before new carpeting is installed, ask your retailer to unroll and air out the carpet in a well-ventilated area. Open windows while carpet is being installed.
  • Utilize exhaust fans in bathrooms and ventilation hoods above stove tops.
  • Ventilate crawl spaces, attics, hobby and work spaces.

Problem #2

  • You experience chronic physical symptoms such as sore throats, dry/itchy skin, nose bleeds or sinus irritation.
  • Your home’s wood floors are shrinking and cracking. Joints in wood furniture are becoming loose or failing.
  • Wallpaper is peeling, while your paint or plaster is starting to crack.
  • Annoying and sometimes painful static shocks are common occurrences.
  • Your thermostat is cranked up, as is your energy bill, but you still feel cold.
  • Your piano and other musical instruments are falling out of tune.
Problem: Dry Air
Primary Solution: Install a whole-home humidifier

Problem #3

  • Your skin often feels clammy, sweaty or sticky.
  • Musty-smelling odors are invading your living space.
  • Wood floors, trim or wood furniture is warping or rotting, paint is peeling.
  • Condensation, frost or ice have formed on the inside surface of your windows. Water pipes are “sweating”.
  • Damp spots, or worse, mold and mildew, have formed on ceilings or walls.
  • Your allergies or asthma have gotten worse due to the growth of mold, mildew and dust mites.
  • Your house is a breeding ground for termites, cockroaches and other pests.
Problem: Too much humidity
Primary Solution: Install a whole-home dehumidifier
Things you can do to help:
  • Use ventilation fans in kitchens and bathrooms when in use. Ensure that your fans are venting directly outside.
  • Cover dirt floor crawlspaces under your house with plastic to act as a vapor barrier.
  • Check to make sure your dryer is vented to the outside. Don’t dry wet clothes on drying racks in the house. Air-dry them outdoors if possible.
  • Ensure air conditioning drip pans are clean and drain lines unobstructed.
  • Fix any water leaks in pipes, toilets, showers, etc.

Problem #4


  • Airborne pollutants – dust, dust mites, pet hair, dander, pollen, particulates from clothing and furniture.
  • Biological contaminants – bacteria, viruses, mold spores, mildew.
  • Odors and vapors – tobacco smoke, cooking grease
Problem: Poor air filtration
Primary Solution: Install a whole-home air cleaner
Things you can do to help:
  • Open windows when weather and other conditions permit.
  • Bathe pets regularly and keep pet beds and litter boxes away from vents.
  • Change your furnace filter according to manufacturer’s recommendations.
  • Run your heating and cooling system blower when vacuuming and dusting to circulate polluted air through your furnace filter.
  • Keep relative humidity between 30 and 60 percent.
  • Make sure kitchen, bathroom and other exhaust fans vent to the outside.
indoor air pollution

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