Comment; Scott is very experienced, extremely knowledgeable and may be able to conduct “virtual” inspections of your property (as does Greg Weatherman) with a local remediator on an audio-visual (videophone) type link. Both of these people are willing to work with/help train “local (to you)” IEP’s so that they can learn more about the requirements for mold illness which are much more strict than typical Environmental Protection Agency (EPA) requirements.
Keywords; Indoor Environmental Professional, IEP, HEPA Vacuum, National Air Duct Cleaners Association, NADCA, Snake Camera Video before & after, Flex duct caution, Air Handler, Mastic seal, IICRC, MERV Filter rating.
ARMOUR APPLIED SCIENCE, LLC 2017
DUCT CLEANING RECOMMENDATIONS
21 DUCT CLEANING RECOMMENDATIONS
Not all of these may apply to your situation. Some smaller cities have limited
contractor choices, do the best you can to get your contractor to meet these
recommendations as best they can.
1. Prefer NADCA (National Air Duct Cleaners Association)
certified/accredited company with trained onsite techs; prefer conformance with
current NADCA standard. Alternative standards or certifications should be
reviewed before accepting. (not all certs are equal). See also the chapter on
HVAC in the IICRC S520 Professional Mold Remediation Standard (2015).
2. Prefer truck mount vacuums. If contractor uses a stand-alone vac system,
it must have HEPA filter on the outlet, and must be inspected and cleaned and in
good condition (inside and out!). Also, must have sufficient volume (power) to
reach long runs at a distance.
3. Tell the company which cleaning chemicals you prefer if they are
necessary; clearly state what chemicals are absolutely prohibited. Test ahead of
time any unknown cleaners that the company wants to use. I prefer no chemicals
at all, but sometimes it’s needed for heavy soil.
4. No disinfectants in the ducts or other parts of the HVAC system, unless
completely rinsed and EPA registered (must see EPA number on label). I prefer
no disinfectants at all, but sometimes it’s needed for special cases. Contact an
Indoor Environmental Professional (IEP) for advice before using.
5. Must use fragrance-free cleaners if they are needed for any special heavy
soil. I prefer no chemicals at all, but sometimes it’s needed for heavy soil.
6. No fogging of anything.
7. No odor removing chemicals. No fragrances. (ozone or hydroxyl for
special cases only upon review and approval)
8. Get snake camera and videos of the before and after – any and all
locations to prove the quality of work.
9. Always use a video snake to inspect ducts that are in the slab to find
problems (always something). Any odor indicates a water and mold/bacteria
problem; water problems must be corrected before cleaning. See IEP for
10. Use caution with flex ducts. Most flex duct can not be cleaned with typical
mechanical cleaning devices. If inspected and have heavy soil, replace if
11. Inspect to see if there are duct linings (fiberglass or other), especially on
the main supply plenums. If visible mold or heavy soil, remove or seal with
approved duct lining sealer. If deteriorated, remove and replace.
12. Inspect humidifier, clean and maintain as needed.
13. A/C coils and drip pans get cleaned; prefer if possible to remove and clean
outside of home (due to the need for chemicals). All cleaning chemicals must be
EPA registered if they are labeled ‘disinfectant” along with cleaner. Must be
14. Blower/fan gets cleaned.
15. Blower/fan plenum/box gets cleaned. Important to inspect the insulation
for heavy dirt and/or mold and/or water stains (which seem to be common from
drips coming down from coils/pan). If the insulation is bad in any way, I
recommend complete removal. Replacement is optional (it’s only for noise).
16. If possible, seal all duct joints and seams (especially returns) with mastic.
Better than foil tape. Never use “duck” style vinyl tape. This is important for ducts
in crawl spaces or attics.
17. If possible, remove the metal pans from returns in order to inspect and
clean the wood surfaces and seal wood seams and cracks where needed.
18. If there is any visible or suspect mold growth in ducts or non-removable
components, or nearby the system, must get a third party IEP to inspect and
assess the situation for cause and remediation procedures. Duct Cleaner may be
able to include the mold cleanup as part of the regular cleaning (see NADCA and
IICRC for guidance). NOTE: this is not “settled spores” in dust from normal air
movement, this is actual mold growth on components due to liquid or vapor in the
19. Replace filter when cleaning is complete. Use at least MERV 10 or higher
if affordable. NOTE: Prefer to upgrade to a 4-inch pleated filter with a MERV
15/16 rating, e.g., AprilAir 5000 or similar. Get at least 2 if not 3 estimates from
reputable full service HVAC installers (i.e., 2 or more major brands). AprilAir sells
direct to the public for DIY installations. NO hydroxyl, photo-cat, ozone, or Ultra-
Violet (UV) light is necessary for proper particulate filtration.
20. If possible, have additional HEPA-filter air scrubbing during and after the
cleaning to “extra” clean the ambient air.
21. Check and Re-balance the supply system after sealing and cleaning. (not
necessary to use test equip, can do with “feel” of air movement and comfort in
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