Indoor air quality has become very important in residential construction. Which means if you have a forced-air heating and cooling system, you probably have to get your ducts cleaned regularly.
How do you know your ducts are being cleaned properly, and that the duct-cleaner is not taking you for an expensive ride? Obviously, you are going to need to know something about the cleaning process to ensure that you are getting what you pay for.
Quick story: I lived for many years in a house with an old-fashioned boiler that used oil to heat the water in the closed (radiator) heating system. It was an old boiler, and residue from the oil used to collect in brown sheets on all four sides and in the brick firebox.
I bought the oil from a fuel-buying cooperative. For a $15 annual fee, I was able to acquire oil for at least 15 cents a gallon cheaper than if I had purchased it from a regular dealer.
For $75 an hour, I could have the oil-burner serviced and the boiler cleaned by a firm provided by the co-op.
The first year, I noticed that there was black smoke coming from the chimney for the first week or so after the boiler had been "cleaned."
The next autumn, I let the cleaner into the basement to tackle the furnace. It was quiet for the first hour, and I assumed he was using a brush to scour the inside of the boiler, or perhaps changing the filter on the oil burner.
Then came the noise of the vacuum cleaner. When I went down to the basement, the vacuum was running, but it was not being used. The inside of the boiler looked as if no one had touched it for years.
The cleaner was outside, smoking a cigarette.
I refused to pay the charge and cleaned it myself.
Funny, there was no black smoke emanating from the chimney after I cleaned it.
The National Air Duct Cleaners Association, a nonprofit trade group, says the most effective way to clean air ducts and ventilation systems is with "source removal."
This requires a contractor to place the system under negative pressure, through the use of a specialized, powerful vacuum.
While the vacuum draws air through the system, devices are inserted into the ducts to dislodge any debris that might be stuck to interior surfaces.
The debris can then travel down the ducts to the vacuum, which removes it from the system and the home.
There are two main types of vacuum collection devices: those mounted on trucks/trailers and portable units.
Truck/trailer mounted equipment is generally more powerful than portable equipment. However, portable equipment can often be brought into your house, and closer to the ductwork.
All vacuum units should be attached to a collection device for safe containment prior to disposal. Any vacuum collection device which exhausts indoors must be high-efficiency particulate arrestance (HEPA) filtered.
A vacuum collection device alone will not clean a system. Methods and tools designed to agitate debris that clings to the insides of the ductwork should be used in conjunction with the collection device.
How often should ducts be cleaned? The association provides no exact times, but suggests that cleaning be done more frequently if there are smokers in the house, or you have pets with high amounts of hair and dander.
Other reasons: water contamination or damage to the home or HVAC system.
If there are people living in your house with allergies or asthma who might be better off if the amount of indoor pollutants is reduced in the heating and cooling system, or if you've just finished renovating or remodeling your house, or if you have just bought the house, then proceed.
The Environmental Protection Agency says "duct cleaning" services typically -- but not always -- range in cost from $450 to $1,000 per heating and cooling system, depending on the services offered, the size of the system to be cleaned, system accessibility, climactic region, and level of contamination" and type of duct material, the association says.
It adds that consumers should be wary of claims by cleaners that their health will be improved if the ducts are cleaned as well as of "blow and go" cleaners who sell services that are usually unnecessary.
There are health benefits to having the systems cleaned, the association says, since ducts can be "a collection source for a variety of contaminants that have the potential to affect health, such as mold, fungi, bacteria, and very small particles of dust."
The removal of such contaminants from the HVAC system and home should be considered as one component in an overall plan to improve indoor air quality, the duct cleaners association says.