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When to Inspect & Clean HVAC Systems?

Posted by Peter Haugen on Wed, Jan 22, 2014 @ 04:04 PM


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This may seem like a pretty basic question but if you think about it, there are many reason to clean an HVAC system.  In NADCA's new ACR Standard they list the following recommendation to clean when: 

  • The HVAC system is contaminated with an accumulation of particulate.
  • The HVAC system performance is compromised due to contamination build-up.

  • The HVAC system has been determined to be a source of unacceptable odors.

  • The HVAC system is discharging visible dirt or debris into the conditioned space.

  • The HVAC system has been contaminated as a result of fire, smoke, and or water damage.

  • The HVAC system has been infested with birds, rodents, insects or their byproducts.

  • The HVAC system has been determined to be at risk for a fire hazard.

  • The HVAC system has become contaminated with construction debris or duct.

  • Mold contamination conditions have reached either Condition 2 or Condition 3 levels.

  • Deterioration of fiber glass duct liner, duct board, or other porous components.

  • As part of an HVAC maintenance program as defined in ANSI/ASHRAE/ACCA Standard 180.

  • As part of the HVAC equipment manufacturers recommended maintenance practices.

  • As part of a proactive energy Management program

  • As part of a proactive indoor air quality management program.

  • As a component to achieve LEED Certification.

  • When a newly installed component or duct has been contaminated with construction and/or other dust and debris.

If there is any question on the need to clean, performing the NADCA Surface Comparison Test is an easy way to demonstrate the need for cleaning. 

All of these are very good reasons to clean an HVAC system.  This list can be used as a good sales tool when you talk to prospective customers.  But there is one thing that you must due in order to verify if many of these conditions exist.  You must look at or inspect the HVAC system! 

Inspection the HVAC System

In residential HVAC systems this typically means looking at the 2-4 supply duct runs, 1-2 return duct runs, the air handler or furnace (and their internal components) and the dryer vent (if you offer dryer vent cleaning services). 

In commercial HVAC systems which are more complex you should inspect at least 10% of the systems components.  This means looking at the air handler (filters, coils, condensate pans/drain lines, dampers, gaskets etc.), any fan coils, supply ductwork and its internal components (registers, dampers, mixing boxes, reheat coils etc), return duct work and its components (grilles, dampers, plenums, etc).  You are basically looking at a representative sample of anything in the air stream.  Plus, other exhausts systems like bathroom, laundry, general. 

The simplest way to document your inspection is to use a digital camera.  You can insert the camera into the ductwork at several locations and take a picture of the pre existing conditions.  You can then show the home owner or building representative the existing conditions by scrolling through the pictures.  This can help you sell the cleaning project.  After cleaning, take another set of pictures at the same locations as your pre cleaning locations.  Again you show the homeowner or building representative the after cleaning pictures to prove to them that you gave done a good job.  If needed, you can download these photos from your digital camera to your laptop or computer and print them for your customer/client.  Proving that you have done a good job, with the before and after pictures, makes your customer happier about paying your invoice but more importantly they are more likely to give you a referral.  You can also use manual inspection systems and robotic systems that let you record, edit and burn a DVD of your before and after inspections.  

Offering inspection/documentation services (especially in the commercial market) can also be a good way to grow your business.  You can grow/strengthen you network of IAQ Professionals as you provide this service and you get first look at HVAC systems that you may be asked to provide a cleaning bid on in the future.  HVAC system inspections are recommended by:

  • ACR (2013) The NADCA Standard for Assessment, Cleaning, Restoration of HVAC Systems

  • ANSI/ASHRAE/ACCA Standard 180 – as part of an HVAC maintenance program.

  • EPA – Building Air Quality: A Guide for Building Owners and Facility Managers

  • NFPA Standard 90A – Standard for the Installation of Air Conditioning and Ventilating System

NADCA offers a “Certified Ventilation System Inspector (CVI)” certification program which can be a valuable credential to have.


There are many reasons to clean HVAC systems but you and your customer can’t be sure it’s needed until you verify the conditions with an inspection.   

If you have any questions about this blog article or other aspects of HVAC system cleaning, contact Peter Haugen, ASCS, CVI at 855-Vac-Systems, 952-808-1619 or phaugen@vacsysint.com

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Tags: air duct cleaning, inspecting, reasons to clean an HVAC system