Air Duct and HVAC Questions, Answered

No one can promise that. The US EPA says duct cleaning has never been shown to actually prevent health problems, and that there is no evidence a light amount of household dust in ducts poses a health risk.

When there is substantial visible mold growth inside hard surface ducts or other system parts, when ducts are infested with vermin, or when ducts are clogged with excessive dust and debris or particles are actually released into the home from supply registers.

ENERGY STAR says check it every month, especially in heavy winter and summer use, and change it at least every three months, sooner if it looks dirty.

The EPA suggests at least MERV 13, or as high a rating as your system fan and filter slot can accommodate. Ask a technician if you are unsure what your system can handle.

The EPA recommends keeping indoor relative humidity below 60 percent, ideally between 30 and 50 percent, to help prevent mold growth.

The CDC advises battery-operated or battery backup CO alarms on every level of the home and near sleeping areas, checked regularly and replaced as the maker directs.

One common reason is a lint-clogged vent duct. Failure to clean is the leading factor in home clothes dryer fires in US Fire Administration data, so clean the lint screen every load and keep the vent clear.

ENERGY STAR says never use duct tape on ducts because it is not long-lasting. Mastic sealant or metal-backed foil tape is used instead.

The EPA warns that ozone is a lung irritant and that, at levels that do not exceed public health standards, ozone has little potential to remove indoor air contaminants. A filter-based air cleaner is the better understood choice for particles.

NADCA, the National Air Duct Cleaners Association, publishes the ACR standard for assessment, cleaning and restoration of HVAC systems and certifies Air Systems Cleaning Specialists.