Range Hood + Venting Service

Why this matters

Range hoods are the kitchen ventilation appliance - moving smoke + grease + heat outdoors during cooking. Code requirement in many jurisdictions (especially gas ranges + induction with above-cooktop venting). Average service. Many customers ignore the hood until it fails OR the kitchen smell tells them it's not working. Tech who can service AND quote replacements builds a steady revenue stream + protects customers from grease-fire risk.

Hood types

Under-cabinet range hood

• Most common residential
• Mounts under wall cabinets above range
• Width: 24", 30", 36" common
• CFM: 200 - 500 typical
• Recirculation (charcoal filter, NO outside vent) OR ducted (vent to exterior)

Wall-mount chimney hood

• Decorative chimney style; visible duct cover
• 30" - 48" widths
• CFM: 400 - 1,200
• Ducted (almost always); recirculation rare in chimney style

Island hood

• Mounts above island cooktop; ceiling-suspended
• 30" - 48" widths
• CFM: 500 - 1,500 (needs more for unobstructed cooking)
• Always ducted; long vent run common

Downdraft / pop-up vent

• Cooktop-side ventilation; rises during use
• Lower CFM but eliminates overhead hood
• Common in island layouts where overhead obstruction is undesired

Microwave with vent (OTR hood/microwave combo)

• Most common in builder-grade kitchens
• CFM: 150 - 400 (insufficient for serious cooking)
• Often the customer's first complaint: "my hood doesn't pull smoke" - usually correct; OTR hoods are weak

Pro / commercial-style hood

• Wall-mount or chimney
• CFM: 800 - 1,500+
• Stainless construction; commercial-grade fans
• Used with professional cooktops + ranges

CFM sizing

• Recommended: 100 CFM per linear foot of cooktop, OR 1 CFM per 100 BTU of gas burner output
• Standard 30" gas cooktop with 60,000 BTU total: 600 CFM minimum
• Pro range (45,000 - 80,000 BTU/burner × 6 burners = 270,000+ BTU): 1,000 - 1,500+ CFM
• High CFM (>400) requires makeup air per IRC (M1503.4) for sealed-house performance

Common failures

Failure 1: Fan won't run

• Switch / control fault
• Motor capacitor fault (AC motors)
• Motor seized
• Wiring damage (heat + grease attack on wires over years)

Diagnostic:

1. Verify power at hood (most are hardwired; some plug-in)
2. Test motor capacitor (test bench OR replace as diagnostic)
3. Test switch continuity
4. If motor + capacitor OK, switch + wiring is the fault

Failure 2: Fan runs but no airflow

• Filter clogged with grease (most common)
• Damper stuck closed (backdraft damper at hood exit)
• Duct obstructed (lint, bird's nest, ice in winter)
• Vent termination cap closed or bird-screen blocked

Diagnostic:

1. Remove filter; clean or replace
2. Inspect damper movement
3. Visual inspection of duct from hood up to termination
4. Check exterior termination cap

Failure 3: Excessive noise

• Worn motor bearings - replace motor or whole hood
• Loose impeller - tighten or replace
• Cabinet vibration - secure mounting
• Duct rattle - secure duct supports

Failure 4: Light doesn't work

• Bulb (most common; halogen + LED replacements available)
• Light switch
• Wiring

Failure 5: Backdraft / outside air entering through hood

• Damper failed open
• High wind + no damper
• Replace damper OR add second damper at exterior cap

Recirculation vs ducted (the big distinction)

Ducted: vents to exterior; removes grease + moisture + heat; preferred whenever possible.

Recirculation: filters grease through charcoal filter + returns air to kitchen. Removes 50 - 70% of grease (with new filter); does NOT remove moisture or heat or much smell. Customers complain because expectations don't match what recirculation can deliver.

Convert recirculation to ducted whenever possible:

1. Determine vent run path: shortest possible to exterior
2. 4 - 6" round duct standard for most residential hoods
3. Rigid duct preferred; flex if curved path; smooth metal interior
4. Minimum bends; maximum 25 - 35 ft equivalent length (varies by hood spec)
5. Terminate at wall or roof cap with backdraft damper
6. Insulate duct in unconditioned spaces

Filter maintenance (most-ignored item)

Grease filters (metal mesh)

• Clean every 1 - 3 months residential
• Dishwasher safe (most)
• Replace if damaged; metal mesh lasts 10+ years with care

Charcoal filters (recirculation only)

• Replace every 3 - 6 months
• DO NOT clean - saturated charcoal can't be regenerated
• Skipped maintenance = recirculation hood becomes a fan moving grease around

Replacement decision

• Hood 10+ years + multiple failures: replace
• Light fault + working fan: repair
• Motor + bearing failure: usually replace whole hood
• CFM inadequate for cooking style: upgrade to higher CFM
• Recirculation to ducted: upgrade opportunity (premium quote)

Code compliance

• Local building code may REQUIRE ducted ventilation for gas ranges
• Makeup air required if installed hood >400 CFM in tight house
• Termination distance from windows + intakes per IRC
• Backdraft damper required at termination

Some local AHJ require permit for new vent install - confirm with customer.

Replacement install (under-cabinet)

1. Disconnect power; disconnect duct; remove screws from inside cabinet; lift old hood out
2. Configure new hood: ducted vs recirc, duct adapter
3. Lift into position; drive screws from inside cabinet bottom into hood top
4. Slip duct over adapter; seal with foil tape (not fabric duct tape); secure with sheet-metal screws
5. Hardwire OR plug-in; verify polarity + ground
6. Power on; verify fan speeds + light + damper; customer walkthrough

References

• IRC (International Residential Code) - M1503 hood requirements
• ASHRAE 62.2 (residential ventilation)
• Manufacturer install guides
• Manuall internal: Oven + Range Service, Appliance Diagnostic Error Codes - Troubleshooting