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). It is a small-ticket service call that turns into an install ticket often enough to be worth carrying parts for. 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 (16,000 - 25,000 BTU/burner x 6 burners = roughly 100,000 - 150,000 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