How to Clean a Dryer Vent

Why a sweep crew sells this

Dryer-vent fires cause ~15,000 U.S. residential fires per year (NFPA + USFA data). Same skill set as chimney sweep: ladder, brush, vacuum, lint = creosote analogue. Customer already trusts the brand; attach rate at sweep visits is 25-40%. Net margin beats the sweep itself because there is no roof harness and the turnaround is faster.

When dryer vents need cleaning

• Annually for typical residential
• Every 6 months if family of 5+ or daily laundry
• Symptoms customer reports: clothes take 2+ cycles to dry, dryer body hot to touch, burning smell, lint visible at exterior hood, no air movement at hood when running

Tools

• Dryer-vent brush kit (flexible nylon brush + 30-50 ft of segmented fiberglass rods)
• Cordless drill (powers the brush rotation)
• HEPA vacuum + crevice tool
• Anemometer (air-flow meter,) - measures before/after
• Camera scope (optional but a great proof point)
• 16 ft extension ladder if vent terminates above grade
• Drop cloth + masking tape

Procedure

Step 1: Locate both ends

Find the dryer (back of laundry room or basement) + the exterior vent termination (typically a wall hood with a flapper). Map the run mentally - straight, one elbow, two elbows? Length? Each elbow = ~5 ft equivalent length; total equivalent length should not exceed 35 ft per IRC + manufacturer spec.

Step 2: Pre-test

Turn dryer on (heat OFF, fan ON). Anemometer at the exterior hood:

• Good: 1200-1800 FPM
• Marginal: 800-1200 FPM
• Failing: < 800 FPM

Record this for before/after proof.

Step 3: Disconnect dryer

1. Pull dryer 18-24" from wall
2. Loosen the clamp at the back of the dryer
3. Disconnect the transition hose
4. Tape a drop cloth to the floor under the dryer
5. Inspect transition hose: if it's plastic/foil flex, replace with rigid or semi-rigid metal at the same visit ( add-on)

Step 4: Brush from outside in

Best practice. Lint travels WITH the airflow, which runs away from the dryer and out the hood, so the packed lint sits at the termination end and at the last elbow before it. Working from the hood inward puts you at the packed end first, and everything you loosen falls out the opening you are standing at instead of into the laundry room.

1. Remove exterior hood cover
2. Insert brush head + 4-6 ft of rod
3. Spin with drill at 600-800 RPM, push + pull
4. Add rod sections as you progress
5. Continue until brush hits the laundry-room wall opening

Step 5: Vacuum from inside

1. HEPA vacuum at the laundry-room wall stub
2. Run for 60 seconds - sucks loose lint released by brushing
3. Reverse vacuum to exterior, run another 30 seconds

Step 6: Vent box + dryer interior

The dryer lint trap is one filter. There's a second lint zone INSIDE the dryer below the lint screen - vacuum the screen housing + the area you can reach with a crevice tool. This is where most of the lint actually accumulates.

Step 7: Exterior hood

1. Hood flapper should move freely - if stuck with lint, clean or replace ( hood)
2. Mesh on hood? Code prohibits screens (NFPA 54 + manufacturer spec). Remove + dispose; note on invoice
3. Bird/animal damage? Document + price replacement

Step 8: Reconnect dryer

1. Replace transition hose if needed (UL 2158A semi-rigid only - never foil/plastic flex anymore)
2. Clamp both ends snug
3. Push dryer back, leaving 2"+ behind for the transition (don't crush)
4. Plug in / connect gas

Step 9: Post-test

Anemometer again at exterior hood. Document the improvement. A 30% airflow increase is the typical "sale closed" number.

Step 10: Show + invoice

Show the customer the lint pile. Photo of the volume - usually 2-5 gallons of lint per typical residential. Photo of the before/after airflow reading. They paid for proof.

Acceptance criteria

• Airflow at hood > 1200 FPM
• No visible lint accumulation in the run
• Transition hose UL 2158A rigid/semi-rigid metal
• Hood flapper operates
• Customer signed + has photos

Common pitfalls

• Pushing the brush in without extracting at the hood: loosened lint rides ahead of the brush and repacks at the elbow nearest the dryer; the customer calls back in 8 weeks. Vacuum at the hood as you withdraw the rods, not just at the end
• Leaving foil/plastic flex: code violation + #1 fire start point; replace every time
• Skipping the dryer interior: returns in 3 months "still slow"
• Not measuring before/after: customer has no proof of value
• Skipping the lint trap housing vacuum: 30% of lint is here
• Not removing exterior screen: customer thinks you missed it
• Aluminum-foil tape on connections: melts; use UL 181-listed foil tape or screw clamps

Safety considerations

• Gas dryer: shut off + cap line during service. If you don't hold a gas license + customer has a gas dryer, do the duct only; refer the appliance side
• Electric: unplug
• Watch lint inhalation: respirator + eye protection
• Brush rotation can grab - never gloves with loose fingers near the drill chuck

Common findings to upsell

• Vent run too long: relocate dryer or reroute ( by GC + sweep)
• Vent run uphill with sags collecting lint: rerouted
• Roof-vented dryer above attic: clogs constantly + animal entry. Quote redirect to side wall
• Dryer in tight closet: needs more space behind for transition

References

• IRC M1502 and IMC 504 for dryer exhaust duct. NFPA 211 is the chimney and solid-fuel standard and is the right reference for the flue work on the same truck, not for this
• IRC M1502 (dryer exhaust)
• UL 2158A (transition duct)
• NFPA + USFA dryer-fire incidence data
• Manuall internal: Chimney Sweep Service SOP