How To Change A Kitchen Hood Fan | Step-By-Step Guide

If your range hood hums, rattles, or barely clears steam, a fresh unit can restore quiet ventilation and better lighting in a single afternoon. This walkthrough gives you a tight plan: what to check in advance, the exact steps to swap the hood, and the fixes for common hiccups. You’ll see how to size the duct, pick the right mounting hardware, and wire it safely. No filler—just the steps and the why behind them, so you can get a clean, code-aware upgrade without headaches.

Changing A Kitchen Hood Fan Safely: Prep Checklist

Good prep makes the install go smoothly and keeps mess to a minimum. Start with a quick survey of the space, the duct path, and the power supply. Then gather the right tools so you’re not climbing up and down the ladder every five minutes.

Tools And Materials

• Tape measure, painter’s tape, pencil
• Stud finder, level, and a square
• No-contact voltage tester and multimeter
• Screwdrivers, nut driver set, drill/driver, step bit
• Sheet-metal screws, mounting anchors, and washers
• Rigid round duct or rectangular transition (match your hood outlet)
• UL-listed metal tape (foil), duct mastic (for exterior caps), and a listed backdraft damper if not included
• Wire connectors (push-in or wirenuts) and cable clamp
• New hood fan with filters, bulbs, and the manufacturer’s template

Broad Planning Table (Fit, Duct, Power)

This table compresses the early decisions so you can verify clearance, venting, and wiring before you unbox anything.

Item	What To Check	Quick Tip
Width & Mount	Cabinet span and hood type (under-cabinet, wall, insert)	Match or exceed cooktop width; confirm screw holes hit solid wood.
Height Above Cooktop	Clearance range in manual (often 24–30 in for electric; check gas)	Mark the finished bottom line with painter’s tape for leveling.
Duct Size	Outlet size on the new hood (e.g., 6 in round or 3¼×10 in)	Don’t neck down; use a proper transition if you must change shapes.
Duct Path	Shortest run to outside; count elbows and total length	Fewer bends moves more air and cuts noise.
Backdraft Damper	Damper in hood or cap present and swinging freely	Add one if missing; screens at the cap block grease.
Power	Hardwired vs. cord-and-plug, breaker size	Shut off at the panel; verify dead with a tester every time.
Makeup Air	Exhaust rate of the new hood (CFM)	Some homes need makeup air when CFM is high; check local rules.

What Codes And Best Practices Say (In Plain Terms)

Two simple ideas guide a good install: move air well, and do it safely. Smooth metal duct with gentle turns keeps airflow strong, while a backdraft damper and an exterior termination keep the kitchen cleaner. The IRC chapter on exhaust systems calls for a damper at the termination and no screens that can trap grease. Many jurisdictions also require makeup air when a hood can pull more than 400 CFM; see IRC M1503 on makeup air for the threshold and conditions. For ducting basics, the Building America Solution Center explains why rigid metal with a smooth interior outperforms flex and reduces cleaning issues. Their retrofit guide is a handy reference for material and layout choices (kitchen exhaust retrofit guide).

Measure, Mark, And Pre-Fit

Dry fitting avoids surprises. Lay the manufacturer’s template against the cabinet bottom or wall. Confirm centerline over the cooktop. Lightly mark anchoring holes and the duct opening. Hold the hood near the marks to check cord reach or junction box location. If you’re using a rectangular-to-round transition, place it now to validate clearance behind the cabinet rail.

Check Duct And Cap

Peek inside the existing duct. If it’s corrugated or crushed, plan to swap it for smooth rigid. Confirm the outside cap opens freely and isn’t screened. If the cap is rusty or caked with grease, replace it while you’re at it. Shorten long runs and reduce elbows where feasible; every turn adds resistance and raises noise.

Confirm Power Type

Open the hood’s wiring compartment and note whether the previous unit was hardwired or plugged in. Many residential hoods allow either method, but follow the manual for your model. A cord-and-plug connection is common in a cabinet above the hood. If you’re hardwiring, ensure the cable has a clamp at the knockout and that all splices sit inside the hood’s junction box with the cover secured.

Step-By-Step: Remove The Old Hood

1. Shut off the correct breaker. Verify with a non-contact tester and then with a meter at the wires.
2. Remove filters and light lenses. This reveals mounting screws and the wiring cover.
3. Open the wiring compartment. Disconnect the splices (hot, neutral, ground). Cap the house wires while you work.
4. Back out the mounting screws or nuts while a helper supports the weight. Lower the hood carefully to avoid scratching the backsplash.
5. Inspect the wall or cabinet. Fill stripped screw holes with toothpicks and wood glue or shift the new fasteners to fresh wood.

Step-By-Step: Install The New Hood

1) Hang The Bracket Or Pilot Screws

Many under-cabinet models hang on two rear keyhole slots. Pre-install those screws, leaving heads proud by a few threads. If the hood uses a wall bracket, level and anchor it into studs. Use washers so the bracket doesn’t tilt when tightened.

2) Set The Duct Connection

Attach the transition or round collar to the hood with sheet-metal screws as directed. Use metal tape on the exterior of each seam. Keep screws short so they don’t protrude into the airflow path. If a backdraft damper is included, check that it swings freely without hitting the cabinet floor or a seam in the transition.

3) Lift And Hook The Hood

With a helper, raise the hood and set it on the keyhole screws or bracket. Slide it into place and tighten. Verify the front edge sits parallel to the cabinet face. A small shim at the rear corners can correct tilt on an uneven cabinet bottom.

4) Connect The Duct

Align the duct to the collar without forcing a sharp bend. Add a short adjustable elbow if needed to meet the existing run. Drive three sheet-metal screws spaced evenly around the collar, then seal the joint with listed foil tape. Where the duct meets the exterior cap, seal the outer joint with mastic to keep rain out.

5) Make The Electrical Splices

Feed the cable through a clamp into the wiring box. Strip insulation cleanly. Connect ground to the green screw or ground wire, neutral to neutral, hot to hot, using listed connectors. Tug each splice to confirm it’s tight, fold the wires neatly, and secure the cover. If the hood uses a plug, install a listed outlet in the cabinet above, with the box secured and the cover plate flush.

6) Final Mounting Screws

Run the remaining mounting screws from inside the hood into the cabinet or wall framing. Tighten until snug; don’t crush thin sheet metal. Reinstall filters and lamps.

Vent Performance Tips That Pay Off

• Keep runs short. Every foot and every elbow adds resistance, which steals CFM and raises noise.
• Use smooth rigid duct. Corrugations in flex catch grease and whistle. Smooth walls move air with less effort.
• Match the outlet size. Reducing from a 6-inch outlet to 4 inches throttles flow and can void warranties.
• Seal smart. Metal tape on seams inside the kitchen; mastic on exterior caps. Regular “duct tape” dries out.
• Mind the damper. A stuck flap invites backdrafts and odors. Test it before you close up.

Tune And Test

Restore power at the breaker. Cycle each speed and the lights. Hold a paper towel near the filters; it should pull tight. Step outside and check that the cap opens and you feel a steady push of air. A light rattle usually points to a loose filter, a misaligned duct collar, or a screw tip catching the damper—easy wins with a small adjustment.

Care After The Install

Oil and steam load up filters, which cuts capture and raises noise. Wash metal mesh filters in hot, soapy water monthly if you cook often. Baffle filters can go in the dishwasher on a gentle cycle. Charcoal filters in recirculating setups need regular replacement per the manual. Wipe the fan housing and lights during filter changes to keep grease from hardening.

When The Old Duct Won’t Cooperate

Sometimes the old run is undersized or crushed behind a rail. If the cabinet layout allows, reroute with a short straight rise and a single elbow to the wall. Where the outlet shape differs (say, your hood is 6-inch round and your run is 3¼×10 rectangular), use a listed transition and allow space above the cabinet floor so the damper doesn’t hit. If the run is long, upsizing the duct can offset losses and reduce drone on high speed.

Cost And Time Benchmarks

Most under-cabinet swaps take 2–4 hours for a straightforward like-for-like replacement with an intact duct and nearby power. Plan more time if you’re converting from recirculating to vented, adding a new exterior cap, or enlarging the duct. Material costs vary, but a typical basket includes the collar/transition, 6-inch rigid pipe and elbows, an exterior cap with damper, metal tape, screws, and a tube of mastic.

Wiring Notes In Plain Language

Range hoods are usually a light-duty load and can be hardwired or cord-and-plug depending on the model. Follow the diagram in your manual and keep all splices inside the built-in box with a cover. Use a proper clamp at the knockout, connect ground first, and secure the plate before you power up. If your new hood specifies a cord, install a receptacle in the cabinet above the unit. Keep the cord away from the hot zone and out of moving parts. When in doubt about circuit sizing or routing, a licensed electrician can set it up cleanly and keep you out of trouble with local inspectors.

Troubleshooting Table: Symptoms, Causes, Fixes

If something feels off after the swap, this table points you to fast checks that solve nine out of ten calls.

Symptom	Likely Cause	Fix
Poor Capture On High	Duct reduced, crushed, or too many elbows	Restore full duct size; replace crushed sections; simplify the run.
High Noise At All Speeds	Small duct or damper scraping a screw tip	Upsize duct if possible; shorten screws; realign collar.
Backdraft Or Odors	Damper stuck or missing; cap screen clogging	Free or replace damper; swap to a cap without a screen.
Lights Work, Fan Dead	Loose motor plug or wrong splice	Kill power; reseat the motor plug; verify hot/neutral/ground.
Grease Drips At The Seam	Unsealed joint at collar or cap	Seal with metal tape (inside) and mastic (outside).
Cabinet Vibrates	Mounting screws in thin panel only	Add fender washers or hit the rail; add a rear bracket.

Sizing Basics For Better Performance

Pick airflow and duct size as a pair. For a typical 30–36-inch cooktop, 250–400 CFM paired with a 6-inch round duct keeps noise in check while clearing steam for daily cooking. Large gas ranges and heavy searing sessions may need more. Once you cross higher flow rates, local rules may ask for makeup air so you don’t pull the house under negative pressure. That’s why checking your model’s CFM rating against local requirements matters. The code page linked above shows the threshold; many jurisdictions follow that pattern.

Quick Do’s And Don’ts

• Do match the duct to the outlet size and keep runs short.
• Do use metal tape on seams and a proper clamp on the wiring entry.
• Do clean filters on a schedule; airflow depends on it.
• Don’t vent into the attic or a crawlspace.
• Don’t add a screen to the cap; it traps grease.
• Don’t crush the damper flap with long screws.

When To Call A Pro

Bring in help if you’re adding a new exterior penetration, running a long duct through finished framing, or relocating power. Gas ranges with high BTU output and custom inserts can involve larger ducts, heavier hoods, and makeup air hardware. A pro can size the run, set the cap in the right spot, and tune noise levels by adjusting the layout and fan speed settings.

Final Checks And Maintenance Plan

Run a quick monthly routine: wash filters, inspect the cap, and wipe the control panel. Every six months, check that screws are snug, the damper swings smoothly, and the tape at the collar is intact. A few minutes of care keeps airflow steady and extends motor life. Your kitchen stays free of lingering smoke, and the lights over the cooktop remain bright and clean.