What is the role of duct cleaning?

When I opened Legacy Custom Builders, Inc. in 1988, I had never heard of a "duct-cleaning" company. Now if you search for duct cleaning services you will find dozens of companies advertising the service. I want to tell you there is a big difference between the proper cleaning of your air conditioning system and a $250 duct cleaning service. Let me show you the difference.

A $250 Wham-Bam Duct Cleaning: 

A duct cleaning company pulls up to your home at 10 a.m. They remove the air conditioning supply registers in your home (usually 8-12) and use a brush-headed vacuum system to clean as much of the ducts as they can see and reach. Approximately two hours later, they have packed up, cleaned up, collected their $250 and are headed to the next of four or five similar jobs that day. Nothing has been done to improve the indoor air quality of your home; you have just wasted $250. You could have purchased a shop vacuum and done the job yourself; your ducts wouldn’t be any cleaner or dirtier, but at least you’d have a good shop vac. 

A Proper Cleaning Of Your Air Conditioning System: 

Duct cleaning is only one component of a proper system cleaning. The air traveling through your supply ducts will re-circulate to your air handling equipment via the return air. It is extremely important that the return air ducts and/or plenum are thoroughly cleaned and checked for air leaks. I have never inspected an air conditioning system that didn’t have some leaking. After sealing and cleaning the return air components, the evaporative coils in your air handler must be thoroughly cleaned. Some dis-assembly of your air conditioning unit is usually required for this step and should only be completed by an air conditioning specialist. Make sure they use a non-toxic cleaner. Remember, whatever they use will be released into the air after they restart the system. 

Your supply ducts should be checked for leaks or disconnected joints. The company doing the work should be using an eight-inch diameter vacuum hose and some sort of duct scrubbing device. A semi-rigid air hose that uses approximately 200 psi pressure and a multi-directional pressure tip is a good scrubber. The high-pressure air dislodges the dirt from the inside walls of your ductwork and is vacuumed to a large vacuum unit that is usually mounted on a truck. Handheld units are not adequate and should only be used in areas of limited access. 

This thorough cleaning and sealing of your return air, evaporative coils, air handler cabinet and supply registers should take two technicians at least half a day on an average-size home with one air conditioning system. Hence, the cost is generally twice what you see advertised by the discount duct cleaning “specialists”. 

So you see, beyond vacuuming the ductwork itself, cracked and unsealed seams and compromised return air systems must also be addressed. However, keep in mind that using the wrong air filter or not changing the filter monthly will promptly undo the cleaning (generally, a one-inch paper pleated filter is safe for all systems). In a properly maintained system, duct cleaning probably isn’t necessary more than every five years.