Q. What is the best method to clean out a dryer vent? I have a variety of types in front of me. Many are the accordion-style flexible pipe, some with dips and trap-like kinks. Can I just shove a dry vacuum nozzle in there and suck out all of the junk? Will its 5 horsepower be enough? You see all of these gadgets that look half-suspicious — like that feather mop-looking thing that you can attach to a drill. Do those work?
ALEXANDER K, Dorchester
A. According to the US Fire Administration, 2,900 home clothes dryer fires are reported each year and cause an estimated five deaths, 100 injuries, and $35 million in property damage. Failure to clean the dryer is the leading cause.
The most efficient and safest dryer ducts are the 4-inch rigid metal ones. The smooth interior of these pipes reduces air flow drag and lint buildup. The flexible white plastic hoses are inefficient and a fire hazard; they become brittle from the heat.
There are also flexible metal hoses, although they tend to build up lint and are best used for connecting the machine to your rigid metal ductwork.
Determining whether your dryer duct is full of lint and in need of cleaning can be straightforward. The clue is noticing whether your clothes dryer is taking longer than usual to dry its contents. If this is the case, you either have an airflow issue or a defective heating element. If your clothes come out hot after the last cycle, then you can probably rule out the heating element.
Inspect the exterior vent flap when the dryer is in use. Make sure there are no obstructions like bird, mouse, or bee nests. The air velocity should open this vent wide. If the exterior flapper barely opens, then your airflow is minimal and your duct probably needs to be cleaned, shortened, or both.
When dryers are located a short distance from an outside wall, the straight duct run works well, requiring little maintenance and making inspections easy. Many laundry rooms today are deeper inside homes, however, which means long runs and several elbows, often resulting in restricted airflow.
As far as cleaning your ducts, I’ve seen people use a shop vacuum from both ends of the dryer vent duct. One home inspector friend of mine uses a battery-powered leaf blower on the inside and a shop vacuum on the outside with good success.
I use a dryer vent-cleaning kit. You can purchase one online or at your hardware store for about $40. These kits are designed to be used with a drill. An auger brush attaches to a flexible rod. The brush head is bendable to get in tight spaces and has a plastic round nose that allows it to navigate in and around pipe elbows. The rotating action of the self-feeding auger brush and flexible rods scours the entire vent surface. The flexible rods are typically 36 inches long. A kit typically comes with enough flexible rods to clean a 12-foot duct.
■ Determine whether it is easier to clean the dryer duct from the inside of the house or the outside.
■ Be sure to wear a dust mask and the proper eye protection.
■ Unplug the dryer from the power source and pull it out from the wall. Detach the dryer duct connection. Use care with gas connections.
■ Attach a flexible rod to the drill and set your drill to spin clockwise at a middle setting.
TIP: As you add more rods, wrap the connections with electrical tape. Do not use your drill in reverse, or the rods will detach.
■ Slowly turn on the drill and move the brush in and out, allowing lint to come back toward your direction and, preferably, into a vacuum.
If you are cleaning the dryer duct from the outside, remove the dryer hood, if possible. If you can’t, use a paper clip to hold open the flapper.
After cleaning the ductwork, reattach it to the dryer and replace the hood. Plug the dryer back in.
TIP: Turn on the dryer and allow all of the loose debris to exit the pipe. Run the brush through the pipe once or twice with the dryer running.
Remove and clean the lint trap.
Rob Robillard is a general contractor, carpenter, editor of AConcordCarpenter.com, and principal of a carpentry and renovation business. Send your questions to firstname.lastname@example.org or tweet them to @robertrobillard. Subscribe to our free real estate newsletter at pages.email.bostonglobe.com/AddressSignUp.