Is Duct Cleaning Useful?

One of the most common questions in my classes is, “What are your thoughts on air duct cleaning?”  I now have an up-to-date resource to share with students.

This month’s Indoor Air Journal has an excellent article on duct cleaning titled, “Is ventilation duct cleaning useful? A review of the scientific evidence.”  The author of the article is M.S. Zuraimi from the National Research Council Canada.

Debate has always swirled around air duct cleaning.  Many professional engineers speak of it being a waste of money.  Many air duct cleaners espouse its benefits on occupant health and equipment efficiency.  I think the best place to start is to describe how dust and debris build up in the first place.

Return ductwork takes air from the space and delivers it back to the air handling unit.  Particles from activities such as cooking or photocopying can get deposited in the return ductwork.  Filters may be placed on the return grilles to reduce the deposition of particles in the return duct, but the most common location for filtration is directly before the cooling or heating coils.

Particles entering into a return (or from outdoor air intakes) have a few potential final destinations: Continue reading