How to Catch Fall IAQ Opportunities

The fall season lacks the extreme temperatures that keep HVAC services in high demand. We’re required to focus on new ways to generate business. Let’s take a look at several points that we can use in our marketing and daily conversations with our customers to benefit both of us.

Oddly enough, when temperatures are mild, Indoor Air Quality (IAQ) begins to suffer. In summer and winter months, many systems operate the majority of the time, struggling to move enough the air and heat to generate comfort. When heating or cooling demand ceases, several other necessary functions such as ventilation, dehumidification and filtration terminate as well.

Since each of these functions is essential to good comfort and IAQ, let’s take a look at our opportunities:

Some ventilation can be provided from open windows and introducing outside air into the building. This air is unfiltered and contains excess humidity. Installing fresh air systems with filtration and dampers is one opportunity. Installing a thermostat that cycles the fan for ventilation is another service that solves the problem.

Fall is also the time to check small bath and kitchen exhaust fans. These open doors to cleaning and replacing exhaust fans. Cleaning a small fan often quadruples airflow having a huge impact on moisture and odor removal from the areas they serve.


When the cooling systems are no longer running, dehumidification from the forced air system also terminates. Consider recommending dehumidification systems to continue the necessary moisture removal when systems are off, especially in the Southern and Eastern U.S. Several manufactures are introducing some exciting new equipment with dehumidification capabilities.

Of course, once the heating systems kick in, dehumidification will begin again. The question is how much damage can occur in the building until that happens.

Most filtration systems accomplish nothing unless air is passing through them. Filtration ties in closely with ventilation but should be considered as a stand-alone system component as well. Choose your filters and size them carefully.

The number one concern with filtration is excessive pressure drop. As filter efficiency increases, static pressure increases. The higher the static pressure drop through filters, the lower the system airflow. Install new filter housings to increase filter surface area to decrease pressure drop or install return air filter grilles. The filter installed to increase air quality actually can be the primary culprit in causing extremely poor indoor air quality. For constant speed fans, the NCI pressure budget is only 20% of the fan rated total external static pressure.

Check installed filter static pressure drops to assure the fan pressure remains below the fan rated pressure.

Many high efficiency filters may require two or more filters to be installed into the system to assure the pressure remains lower then the fan rated pressure.

Rob “Doc” Falke serves the industry as president of National Comfort Institute a training company specializing in measuring, rating, improving and verifying HVAC system performance. If you're an HVAC contractor or technician interested in measuring filter pressure drop, contact Doc at [email protected] or call him at 800-633-7058. Go to NCI’s website at for free information, technical articles and downloads.

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