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 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 duct work. Simply take the handle of your brush and begin tapping on any accessible duct work 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 loose 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.
9. Replace 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. Refer to Dan Reed