Replace a Bathroom Exhaust Fan

A working bathroom fan removes moisture, prevents mold, and gets rid of odors. Swapping a noisy or weak fan for a new quiet (1.5 sone or less) one is a 1–2 hour DIY that needs no special skills beyond turning off the power.

Difficulty: Medium Time: 1–2 hr Cost: $60–$150
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Turn off the breaker firstDon't rely on the wall switch — switch off the actual circuit breaker and use a non-contact voltage tester to confirm the wires are dead before touching them.

Tools

Materials

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    Match the existing duct size (3-inch or 4-inch) and pick a quiet model (1.5 sones or less). Panasonic WhisperCeiling and Broan QTX series are the standards.
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    For sealing the duct connection — NOT cloth duct tape, which fails on metal
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    Optional, for sealing trim ring to ceiling
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Steps

  1. 1

    Identify the existing fan duct size

    Climb in the attic above the fan or look up through the existing housing. Note duct diameter (3" or 4") — buy a matching fan, not one with a different duct size.

  2. 2

    Kill power and verify

    Flip the breaker for the bathroom circuit. Flip the fan switch — confirm fan does NOT run. Use a non-contact voltage tester on the wires inside the fan housing to be sure.

  3. 3

    Remove the old grille and fan

    Pull down the grille (most pop out by squeezing spring clips). Inside the housing, you'll see the motor and a small junction box. Disconnect the wires (cap and label), the duct (slide off), and the screws holding the housing to the framing.

  4. 4

    Drop the old housing

    With wiring and duct disconnected, the housing slides down through the ceiling cutout. Save it as a reference for the new opening size.

  5. 5

    Test-fit the new housing

    Most new fans fit standard 7-1/4 x 7-1/4" openings. If your new fan is larger, score the drywall with a utility knife and snap to enlarge.

  6. 6

    Wire the new fan

    In the junction box: black-to-black, white-to-white, ground-to-ground (or to the green screw). Cap with wire nuts and gently tuck wires back.

  7. 7

    Reattach the duct

    Slide the duct over the new fan's outlet collar. Wrap with foil duct tape to seal — air leaks here dump moisture into the attic instead of outside.

  8. 8

    Secure housing and reinstall grille

    Screw the housing to the joist, then snap the new grille spring clips into the slots inside the housing. Restore power and test.

    Tip: If you notice condensation in the attic duct after install, wrap the duct with R-6 insulated sleeve — it prevents the warm bathroom air from condensing in cold attic ducts.
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