How to Clean Ducts Yourself

Over time, HVAC ducts normally build up dust, pet hair, dirt, and pollen. Sometimes, ducts develop mold or they trap larger items like construction debris, vermin, or insects. DIY duct cleaning lets you clean your house's HVAC supply and return vents for far less cost than professional duct cleaning.

When to Clean Your Air Ducts

For seasonal HVAC systems that operate only at certain times of the year, clean the air ducts about a month before you plan to reactivate the HVAC system. Cleaning air ducts is beneficial for people experiencing severe allergies since the process reduces allergens.

Otherwise, clean the air ducts on an as-needed basis. If the house smells musty when you turn on the HVAC system or if you smell rodent droppings, clean the air ducts immediately.

Clean air ducts yourself, too, after an unusual event, such as installing a new HVAC system, having major repairs, or a dust-creating house remodeling project. Dust and debris that were not moved previously may be moved by running the blower at higher volumes.

It's important to clean air ducts when mold and mildew are present. If mold is present, contact a professional HVAC service that will use the proper cleaners to completely remove mold from the system. 

How HVAC Ducts Work

HVAC air ducts operate as a continuous loop. Air from the centrally located AC unit or furnace flows through supply ducts and out into the rooms. This air then returns to the central unit via the return duct.

Supply Ducts

Supply ducts blow warm air or cold air into the rooms. Supply duct registers should be located in most rooms of the house, though some rooms may not be served.

Supply registers are covered with plastic or metal grilles and are found on the floor, on exterior walls, in the ceiling, or under windows.

Supply ducts tend to be cleaner than the return ducts. That's because the air first passes through a filter before it makes its way to the various supply registers throughout the house.

Return Air Duct

A large return air vent removes the air from the rooms and returns it to the AC or furnace system. The return is usually located in the wall, close to the floor level.

The return air duct is always dirtier than the supply ducts. That's because dirty, unfiltered air from within the home is being drawn down the return duct on its way back to the HVAC system.

DIY Duct Cleaning vs. Professional Duct Cleaning

DIY duct cleaning differs from professional duct cleaning because the professional machines are unavailable to do-it-yourselfers and are hard to duplicate on a DIY basis. This modified, DIY version of professional duct cleaning clears debris from much of the ductwork but does not address the entire system.

Dislodging Contaminants

In HVAC ductwork, many of the contaminants are attached to the sides of the ducts or are too heavy to be dislodged by air pressure alone. They need to be physically dislodged.

With professional duct cleaning, special tools used to clean air ducts include brushes or air whips attached to compressed air hoses, hand-brushing, or contact vacuuming. Professional negative air machines, too, are so powerful that they can dislodge many of the contaminants.

With DIY duct cleaning, a chimney cleaning head attached to 10 feet of flexible nylon rods is sent through the supply and return ductwork. Rotated by an electric drill, the chimney head cleans much of the ductwork but cannot touch all sides of the duct, nor does it move with as much force as a professional duct cleaning company's compressed air-driven whip cleaner.

Removing Contaminants

With professional duct cleaning, while the contaminants are being mechanically dislodged, negative air pressure is applied to the air ducts. This moves the contaminants backward from the return air or supply vents to the main unit.

Air duct cleaning professionals may have to cut into the sheet metal ductwork near the air handler. This allows access to the collected contaminants. The hole is sealed up after the job is done.

With DIY duct cleaning, the contaminants are pulled forward to the vents, not backward to the furnace or AC.

Safety Considerations

Wear a dust mask when cleaning your ducts yourself. Removing dust can trigger allergies.

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Pros and Cons of Duct Cleaning

Pros

• May possibly improve the efficiency of your system
• Could result in energy and maintenance cost savings
• May control moisture in ducts that leads to biological growth (mold) in system

Cons

• Unproven to actually prevent health problems
• Improper duct cleaning procedures may cause more indoor air problems
• Controversies over introducing chemical biocides or ozone into ductwork in a home