Best Quiet Window Fans

Start with Vornado PORTAL for a compact window installation: its manual specifies a 24–38-inch width range, an opening at least 8 inches tall and electronic intake/exhaust reversal. Choose Air King 9155 if closing the window behind the mounted fan matters most. These are picks for documented fit and controls; the available noise evidence does not establish a quietest winner.

Quick picks

Compare specifications and all conditions

Vornado PORTAL, US

Choose it for

Best compact fit

Window opening

Manual: 24–38 inches wide; at least 8 inches tall; single-hung or double-hung

Airflow and controls

Three speeds; button-controlled direct/exhaust reversal

All specifications

Mounting and closure

Lowered sash secures fan; Soft-Fit foam blocks fill the sides

Air King 9155, US

Choose it for

Best for closing the window behind the fan

Window opening

Spec sheet: 26.5–34.5 inches wide; 22-inch height; linked manual describes double-hung installation

Airflow and controls

Rotary switch; three intake and three exhaust speeds

All specifications

Mounting and closure

Screw-mounted Storm Guard panels let the window close behind it

Full comparison table ↔

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Pick	Choose it for	Window opening	Airflow and controls	Mounting and closure
Vornado PORTAL, US	Best compact fit	Manual: 24–38 inches wide; at least 8 inches tall; single-hung or double-hung	Three speeds; button-controlled direct/exhaust reversal	Lowered sash secures fan; Soft-Fit foam blocks fill the sides
Air King 9155, US	Best for closing the window behind the fan	Spec sheet: 26.5–34.5 inches wide; 22-inch height; linked manual describes double-hung installation	Rotary switch; three intake and three exhaust speeds	Screw-mounted Storm Guard panels let the window close behind it

Pick	Choose it for	Window opening	Airflow and controls	Mounting and closure
Vornado PORTAL, US	Best compact fit	Manual: 24–38 inches wide; at least 8 inches tall; single-hung or double-hung	Three speeds; button-controlled direct/exhaust reversal	Lowered sash secures fan; Soft-Fit foam blocks fill the sides
Air King 9155, US	Best for closing the window behind the fan	Spec sheet: 26.5–34.5 inches wide; 22-inch height; linked manual describes double-hung installation	Rotary switch; three intake and three exhaust speeds	Screw-mounted Storm Guard panels let the window close behind it

PORTAL's required opening is at least 8 inches tall; Air King's required opening height is 22". Measure the usable opening before comparing controls, using the PORTAL guide and 9155 dimensional sheet.

• 8 inchesPORTAL's minimum opening height in its installation guide
• 22"Air King 9155's required opening height on its spec sheet

Best compact fit: Vornado PORTAL

PORTAL earns this pick because its installation guide describes a specific, compact fit: single-hung and double-hung windows, horizontal installation only, with a Soft-Fit modular foam block system. Its controls section documents three speeds—low, medium and high—and a button that switches between direct airflow and exhaust. Choose it when that fit and straightforward adjustment cover your needs.

Installation uses the window itself: center the fan with its bottom foam snug in the casing, lower the sash to secure it, then tuck the side blocks into place. Vornado recommends retaining the screen and keeping a hand on the product throughout installation. This is a useful mounting sequence to compare with your actual sill before ordering.

The guide lists an 8-foot power cord and a weather-resistant enclosure. The separate safety instructions say window units must have their controls facing indoors and their cord and plug kept away from water. Regard those instructions as part of the installation, including where the outlet sits.

The limitation: we did not establish a noise rating from PORTAL's guide. Its controls section also supplies no thermostat procedure, although a troubleshooting row mentions AUTO and a preset temperature. That inconsistency does not establish a thermostat feature; get written confirmation if automatic temperature control is essential.

See PORTAL at Vornado · Read its use and care guide

Best for closing the window behind the fan: Air King 9155

Air King's advantage is its Storm Guard mounting, which the maker says allows the window to close behind the fan without removing it. The 9155 spec sheet requires a 26.5–34.5-inch-wide opening with a 22-inch height. Its depth is 8.25 inches, so compare the mounting drawings with your sill and trim as well as the opening dimensions.

The linked manual is labelled 9155J. It describes mounting inside or outside the interior trim, using screws and screwdrivers, for common double-hung windows. Air King's product page lists the assembled fan with Storm Guard slider panels, mounting hardware and a user manual as the supplied kit. This is the option to consider if you can use that mounting method and want to leave the fan attached when closing the window.

The motor reverses electrically, with three intake and three exhaust speeds selected using a rotary switch. That gives you a fixed direction and speed without a programmed temperature sequence in the documented operating procedure.

The limitation: the base 9155 spec sheet and linked 9155J manual disagree on sound and airflow values. Keep that revision distinction attached to the figures below; confirm the label and applicable specification before buying for a particular noise level. The mounting arrangement is the reason for this pick.

See the 9155 at Air King · Read the linked 9155J manual

Published noise: compare the speed and the document

Air King's 9155 sheet labels its sound columns DB A, with 64 / 50 / 47 for high / medium / low. Its linked 9155J manual labels the row dB A, with 62 / 51 / 48 in the same speed order. Neither PDF states a measurement distance alongside those figures.

These are unresolved maker specifications, not a common-condition comparison. OSHA explains that sound pressure depends on distance and surroundings, and that weighting is identified by letters such as dBA. Request the exact model revision, speed, weighting and measurement distance before treating a small numerical difference as a buying advantage. The Air King manual's AMCA footnote is attached to its CFM row; it does not supply the missing noise distance.

How we choose

This is a document-based shortlist, with no physical testing by thisHUSH. We prioritize explicit window dimensions, mounting instructions, airflow direction and controls in official manuals and specifications. Vornado's current catalogue identifies the Vornado-branded PORTAL separately from TRANSOM and TRANSOM AE; Air King's product page links the 9155 documentation. Unresolved figures stay visible, and no noise winner is inferred from missing data. Our full approach is on How we choose.

Buying guide: check the whole installation

Measure the opening and identify the window

Measure where the fan and its side pieces will sit, then compare the manual's required opening with your available width and height. Do not substitute a cabinet dimension for installation clearance. PORTAL's guide expressly prohibits vertical installation; Air King's manual describes common double-hung windows. Neither is a documented recommendation here for a sideways slider or casement installation.

For a room where the window arrangement does not fit either manual, use our quiet indoor fan guide to consider floor or desk placement instead. Keep that buying decision separate from securing an appliance in an opening.

1. 1

   Identify the window

   Match its opening direction to the exact model's installation instructions.

2. 2

   Measure usable clearance

   Check width, height, sill and trim against the required opening and mounting drawings.

3. 3

   Choose the mounting method

   PORTAL is secured by the sash; Air King's screw-mounted arrangement permits closure behind it.

4. 4

   Check the complete kit

   Confirm side pieces, hardware and the matching manual before ordering.

Decide what reversible airflow must do

PORTAL documents switching from direct airflow to exhaust; Air King documents intake and exhaust speeds. Those instructions do not establish a simultaneous intake-and-exhaust exchange mode. If that is your requirement, insist on an explicit exchange-mode description for the exact model rather than buying on the word “reversible.”

If you want a steady setting, choose and retain a manual speed. For a separate sound source with selectable noise types, see our white noise machine guide.

Check the kit, outlet and window closure

For PORTAL, confirm the Soft-Fit side blocks needed for your opening; its guide also describes optional cord-routing clips. Do not infer a block count from another PORTAL-branded kit. For Air King, the maker lists Storm Guard panels and mounting hardware, but the installation instructions require screwdrivers. Check permission to fasten into your trim before choosing that arrangement.

Plan the outlet route before ordering. PORTAL documents an 8-foot cord; the Air King manual specifies a 6-foot cord and a three-prong grounded plug. Air King instructs buyers to avoid extension cords and power strips. If the supplied cord cannot reach a suitable outlet, reconsider the location or the fan.

PORTAL's installation requires lowering the sash onto the fan. Air King's Storm Guard system explicitly supports closing the window behind it. Do not assume an electronically reversed or switched-off fan restores a closed window; check the physical mounting arrangement.

Follow the weather and cleaning instructions

Vornado describes PORTAL's enclosure as weather resistant, while its window-unit safety instructions keep the controls indoors and the cord and plug out of water. Those instructions also require powering off and unplugging during electrical storms or an extended unattended absence. Air King's manual prohibits outdoor or wet-location use; use its documented window mounting and closure arrangement.

For cleaning, PORTAL's guide calls for unplugging, vacuuming accumulated dust with a brush attachment and wiping the unit with a soft cloth. Air King specifies unplugging before service, cleaning with a soft cloth and mild soap solution, and drying parts before reconnecting. Its storage instruction is a clean, dry place. Keep the matching manual with the fan for the next installation.

Variants and candidates to check carefully

Vornado PORTAL versus Sharper Image PORTAL. The pick here is the Vornado-branded unit. Its use and care guide gives a five-year warranty; the Sharper Image guide covers PORTAL and PORTAL XT with a two-year warranty. These documents do not establish interchangeable kits or warranty terms. Match the brand on the offer and box, then check the supplied installation pieces.

TRANSOM versus TRANSOM AE. Vornado lists these separately. The standard TRANSOM guide documents four speeds, a thermostat, a remote and auto-dimming controls. We retrieved that guide but could not complete the current product-page clearance audit, so TRANSOM is not a ranked pick here. Use its model-specific guide and obtain current fit confirmation from Vornado if those controls are your priority.

The Bionaire candidate is also not ranked: we could not establish a current official US retail kit with matching installation documentation during this audit. A model's appearance on an older shortlist is not enough for nomination here.

• Yes: Match the brand and model on the box to the manual
• Yes: Confirm the side pieces and mounting hardware for your opening
• Partly: Air King noise figures need model-revision confirmation
• No: Do not transfer thermostat features from TRANSOM to PORTAL

Verdict

Choose Vornado PORTAL for its documented compact fit and simple reversible controls. Choose Air King 9155 for its window-closing mounting arrangement, allowing for the larger opening and screw installation. Neither earns a “quietest” award from this evidence; confirm Air King's revision and obtain comparable noise conditions if sound level decides the purchase.

Sources

Official documentation checked November 2, 2026:

• Vornado: PORTAL use and care guide, window-unit safety instructions, current product catalogue and standard TRANSOM guide.
• Air King: window-fan product page, 9155 specification sheet and linked 9155J operating manual.
• Sharper Image Home Comfort: PORTAL / PORTAL XT guide.
• OSHA: Technical Manual: sound pressure and weighting.