Moisture should not be present in ducts. Controlling moisture is the most effective way to
prevent biological growth in air ducts.

Moisture can enter the duct system through leaks or if the system has been improperly
installed or serviced. Research suggests that condensation (which occurs when a surface
temperature is lower than the dew point temperature of the surrounding air) on or near cooling
coils of air conditioning units is a major factor in moisture contamination of the system. The
presence of condensation or high relative humidity is an important indicator of the potential for
mold growth on any type of duct. Controlling moisture can often be difficult, but here are some
steps you can take:(1)

1. Promptly and properly repair any leaks or water damage.

2. Pay particular attention to cooling coils, which are designed to remove water from the air
and can be a major source of moisture contamination of the system that can lead to mold
growth. Make sure the condensate pan drains properly. The presence of substantial
standing water and/or debris indicates a problem requiring immediate attention. Check any
insulation near cooling coils for wet spots.

3. Make sure ducts are properly sealed and insulated in all non-air-conditioned spaces (e.g.,
attics and crawl spaces). This will help to prevent moisture due to condensation from
entering the system and is important to make the system work as intended. To prevent
water condensation, the heating and cooling system must be properly insulated.

4. If you are replacing your air conditioning system, make sure that the unit is the proper size
for your needs and that all ducts are sealed at the joints. A unit that is too big will cycle on
and off frequently, resulting in poor moisture removal, particularly in areas with high
humidity. Also, make sure that your new system is designed to manage condensation

Routine duct cleaning should also be done. If you ever suspect that moisture and or mold is
occurring, get a Licensed Mold Consultant out to asses for mold growth. Have them provide a
protocol for the remediation of any mold growth in the HVAC, Ducts and/or on the HVAC or ducts.

Read more here on how to prevent ducts from becoming wet and contaminated




Emily RachalAbout the Author

Emily Rachal is co-owner of Texas Mold Inspectors, (or TMI), along with her husband, in the Houston, TX area.  After her family’s devastating experience that not only injured her whole family, but also resulted in the loss of their youngest son Malachi, she and her husband have dedicated their lives to now educating and assisting families affected by toxic mold with their state-licensed mold inspection company.

Emily is the founder and owner of MAM. Additionally, she has recently started a non-profit organization in the name of her youngest son, called Malachi’s Message Foundation, to aid in financial support and offer hope to families who feel isolated and are unable to afford all the complex obstacles of overcoming a toxic mold exposure.

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