The negative air pressure method is the best and most result-oriented for cleaning air ducts. This style of air duct cleaning focuses on vacuuming debris that builds up on the walls of the air ducts and then spraying an antimicrobial spray to prevent re-contamination. Negative pressure is arguably the best way to clean an air duct, as it prevents dirt from settling in the air and the antimicrobial spray prevents more from accumulating. Air compressors, vacuums and other pneumatic tools make it easy to clean air ducts air.
Air cleaning can be faster than other methods and reach places where brushes can't. It's not as thorough as cleaning with brushes. These products are specifically designed for use in conduits or as actual conduits, and are tested in accordance with standards established by Underwriters Laboratories (UL), the American Society for Testing and Materials (ASTM) and the National Fire Protection Association (NFPA). While the debate over the value of regular duct cleaning continues, there is no evidence to suggest that such cleaning is harmful, provided it is done correctly.
To find companies that provide duct cleaning services, check the yellow pages on duct cleaning or contact the National Air Duct Cleaners Association (NADCA) at the address and phone number listed in the information section at the end of this guide. When service providers come to your home, ask them to show you the contamination that would justify cleaning the ducts. Knowledge about cleaning air ducts is in its early stages, so a general recommendation cannot be given as to whether you should clean the air ducts in your home. However, there is little evidence that cleaning just the ducts improves system efficiency. Duct breaks are rare, as most professional air duct cleaning services are particularly careful and thorough with this cleaning method.
Just as you wouldn't clean just half the floor in your living room, you wouldn't clean part of your HVAC system either. This is because much of the dirt in the air ducts adheres to the duct surfaces and doesn't necessarily enter the living room. Manufacturers of products marketed to coat and encapsulate duct surfaces claim that these sealants prevent dust and dirt particles inside air ducts from being released to air. This type of cleaning method involves an external machine that separates contaminants from the duct.
As in a household with pets, there will always be something to clean, but cleaning the ducts has definitely helped improve air quality and reduce dust. While many of these products can legally be used inside uncoated ducts if all instructions on the label are followed, some of the instructions on the label may not be appropriate for use in ducts. If all components of the system are not cleaned, the entire system can be re-contaminated, minimizing the benefits of cleaning. Duct cleaning methods vary, although industry associations that deal with cleaning air ducts have established standards.
