There are many reasons to clean the air ducts in your home. When ducts are clean, the heating system lasts longer (because there is less dirt wearing out its components), we dust less often, and the air we breathe at home is cleaner. For those of us with allergies, this should be a welcome improvement.
Probably you don’t own a high-powered, truck-mounted vacuum system with 150 foot-hoses; perhaps you can't afford the cost of such service. But I am going to tell you how you can clean air ducts yourself. Sure, you won't be able to reach every nook and cranny, but you can still eliminate roughly 85% of the dust in your system without spending any more than the cost of your new furnace filter.
There are many different designs of duct systems, such as attic systems and underground systems, but the theory of cleaning these systems is the same. You may not be able to access all parts of these systems (for example, underground ducts), but you can make a difference in your air quality by cleaning the parts of the system that you can reach.
Before we get started, check out this video of what one of those high-powered, truck-mounted vacuum systems looks like at work on a pretty neglected duct system.
- Furnace Filter. You will definitely need a new furnace filter at the end of the job. Make sure you choose the right filter option for you.
- Vacuum. A household-type vacuum with a decent hose attached will work, but a heavier-duty "Shop Vac" unit is better, if available.
- Brush. Something closely resembling a toilet brush will work best, but a stiff-bristle paintbrush or something similar will do.
- Screwdriver or Hex Driver. Your registers are likely held in place by some kind of fasteners. You will need to use whatever tool fits the fasteners, usually a Phillips screwdriver or 1/4" hex driver.
- Paper Towels. Unless you want to do a lot of dusting and sweeping right after you clean your ducts, you will find these useful to cover some registers while you clean others.
Step-By-Step Duct Cleaning
1. Cover supply registers. Start by covering up your supply air registers (openings that supply heated air to the rooms) with paper towels. You do this to keep dislodged dust from drifting into the rooms as you work. Simply lift the register, wrap the paper towel over the top of it, and replace it.
2. Turn on the fan. You want the fan running while you are cleaning, to move the dust along that you are going to loosen with your banging and brushing. Set the thermostat to "fan on," and shut off the "heat/cool" mode so that only the fan is running. If you don't have a fan-only option, you can run the heat, or you might take this opportunity to install a newer thermostat with this helpful option.
3. Check filter. Make sure your old furnace filter is in place so that the dust you knock loose doesn't end up getting pulled into the fan motor.
4. Loosen dust in ducts. Knock loose any buildup of dust in the ductwork. Simply take the handle of your brush and begin tapping on any accessible ductwork you have in the basement. This will help break up any deposits of dampened dust that may have stuck to the insides of the duct.
5. Clean supply registers. Now you can start sweeping out the dust in your supply registers. With the vacuum running and the end of the hose near the register, lift the register. Use the hose to catch any dust that is being pushed out by the fan, and proceed to sweep as far into the register's piping as your hose can reach. Use your brush to scuff lose any built-up dust in the register. As you go through the house sweeping out the supply registers, you can remove and dispose of the paper towels you've put in place.
6. Clean return air registers. Sweep out your return air registers. These will likely be fastened with a screw and require your tool to remove them. Again, brush and sweep as far back into the register piping or cavity as you can.
7. Shut off fan and furnace. Shut the fan off at the thermostat and the power off to the furnace via the service switch or breaker panel. Do not just shut off the thermostat, because that doesn't turn off the power to the unit.
8. Clean out blower compartment and return air boot. With the power off, you can remove the panels on the front of the furnace and access the blower compartment and the return air boot. Use your vacuum to sweep up the dust built up in the blower compartment and return air boot. This is where the great bulk of your dust will be. Since you’re in here, you should clean the furnace fan as well. Have a look at the detailed article (with pictures) I wrote, How to Clean a Furnace Fan for a guide on doing this.
9. Replace the furnace filter. Buying a better filter will definitely cut down on the dust in your home. But the better the filter, the more often you should change it; a dirty filter restricts the airflow to the fan, which results in the blower motor running hotter and reducing its lifespan. How often you should change your filter depends on your home, your pets, and your location.
My Furnace Filter Recommendation: Filtrete MPR 1000's
I'm asked a lot about what filter I use. I prefer these Filtrete MPR 1000 filters. They filter a majority of the bad stuff that could be circulating through your home's ductwork, do a great job keeping the ducts clean over the long haul, and they aren't such a tight filter that they need replacing too often (like the MPR 1500s for example). They're just a really good balance between good air and low maintenance.
Accessing Main Ducts
The areas you could not reach with the steps above are not likely to contain a lot of dust and dirt. However, if you are determined to clean every place you can, there are a couple more things you can do.
1. Remove end caps from rectangular ductwork. If you have rectangular ductwork, like in the picture below, you can remove the end caps to access the inside of the ducts. You can slide the "drives" down off the duct and pull the cap out of the "slips." So long as the duct is not butting up against the wall, you should be able to reach your vacuum hose in through the space uncovered by removing the cap and sweep out any dust you find. You could even use a flashlight to look inside the duct for dirty areas.
2. Clean inside basement registers. Often ductwork will include registers installed throughout the system to distribute air to the basement. If you remove these registers, you'll gain even further access to the main trunk line.
If you do what you can of the items above, you will have made a significant dent in the dust in your environment, and you will have done the best you can, short of calling a professional air duct cleaning company.