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%. Service price. Net margin > sweep itself because no roof harness + faster turnaround.

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 airflow toward the dryer; brushing same direction packs less.

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

• Brushing TOWARD dryer: packs lint at the elbow nearest dryer; future clog 8 weeks later
• 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

• NFPA 211 (chimneys + dryer vents)
• IRC M1502 (dryer exhaust)
• UL 2158A (transition duct)
• NFPA + USFA dryer-fire incidence data
• Manuall internal: Chimney Sweep Service SOP