Broan-NuTone 688 Bathroom Fan: The Complete Buying Guide

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Finding the right bathroom exhaust fan is critical for preventing mold growth and eliminating lingering odors. The Broan-NuTone 50 CFM Ceiling and Wall Bathroom Exhaust Fan is widely regarded as one of the most dependable, budget-friendly ventilation solutions for small bathrooms, and this comprehensive buying guide covers everything you need to know before purchasing.

Broan-NuTone 50 CFM Ceiling and Wall Bathroom Exhaust Fan

The Broan-NuTone 688 is a ceiling and wall-mountable ventilation fan designed primarily for small bathrooms, powder rooms, and utility spaces. It moves air at 50 CFM (cubic feet per minute), which meets the Home Ventilating Institute (HVI) minimum recommendation for rooms up to 50 square feet. The motor is permanently lubricated, meaning you won't need to oil it periodically, and the polymeric fan blade is engineered to resist warping and corrosion in humid conditions.

Get the Broan-NuTone 50 CFM Bathroom Exhaust Fan for reliable, budget-friendly ventilation.

From a build standpoint, the 688 keeps things intentionally simple. The housing is constructed from durable galvanized steel, and the polymeric grille snaps on and off without tools — a small but genuinely useful detail when it comes time for cleaning or bulb replacement on the 688C model that includes a 7-watt night light. Mounting is done with either a standard joist installation or wall-box mounting, making it versatile enough for bathrooms where ceiling access is limited. If you are updating other bathroom fixtures, our Delta Essa 14453LF-SS buying guide for modern baths offers great tips for modernizing your space. You might also consider improving your water quality with a GE GXWH40L Whole House Water Filter to protect new fixtures.

Noise is measured at 4.0 sones, which is noticeably louder than premium whisper-quiet models that hover around 0.3–1.5 sones. However, for a budget-tier fan, 4.0 sones is entirely expected and workable — it's roughly comparable to a running kitchen exhaust fan or moderate rainfall heard indoors. Most users find it easy to tune out, especially during a shower. Broan backs the fan with a 3-year limited warranty, which is competitive in the entry-level segment.

Looking for a reliable, basic exhaust solution? Check the Broan-NuTone 50 CFM fan for current pricing.

The 688 is HVI certified and UL Listed. The 688ES variant additionally carries Energy Star certification — worth noting if energy efficiency ratings matter for your project or local rebate programs. Operating on a standard 120V circuit, it draws a low amperage load and is easy to wire into most existing bathroom electrical setups. The overall footprint is compact — the grille measures approximately 7.25 × 7.25 inches — so it blends unobtrusively into most bathroom ceilings.

Comprehensive Buyer's Guide: Understanding Bathroom Ventilation

Choosing a fan like the Broan-NuTone 688 requires an understanding of the physics of moisture and airflow. When you shower, you introduce a significant amount of water vapor into a confined space. If this moisture is not evacuated, it condenses on cold surfaces—mirrors, walls, and ceilings—leading to peeling paint, mildew, and structural decay over time. This is why CFM (Cubic Feet per Minute) is the most critical metric for any buyer.

Calculating the Right CFM for Your Space

The industry standard for bathroom ventilation is a simple calculation: 1 CFM per square foot of floor area. For a standard 5' x 10' bathroom (50 square feet), a 50 CFM fan like the 688 is the perfect match. However, there are variables that may require you to "over-spec" your fan. If you have exceptionally high ceilings (over 8 feet), you should increase your CFM requirement by 10% to 20% because the volume of air to be moved is greater.

Furthermore, if your bathroom is shared by multiple people or has poor natural ventilation (no windows), increasing the CFM ensures that the air is refreshed more quickly. For those also upgrading home safety, consider checking out our ADT Self Setup 9-Piece Kit buying guide. For those struggling with extreme moisture, our GE ADEL50LZ dehumidifier buying guide (and our detailed review) can provide additional tips on managing damp rooms. While the 688 is ideal for powder rooms, a primary suite with a walk-in shower often requires 80 to 110 CFM to prevent the "steam room" effect from lingering for hours after a shower; in these cases, our Panasonic WhisperGreen Select buying guide can help you choose a more powerful unit (see our detailed performance review) like the Panasonic WhisperGreen Select. For real-world noise levels and performance data, see our detailed review of the WhisperGreen Select.

Sones and the Psychology of Noise

Sones are a logarithmic unit of loudness. A rating of 1.0 sone is roughly the sound of a quiet refrigerator. The Broan-NuTone 688 is rated at 4.0 sones. For many, this is a non-issue in a bathroom setting where the sound of running water often masks the fan. However, it is important to distinguish between "loud" and "annoying." A 4.0 sone fan with a smooth, consistent hum is often more tolerable than a 2.0 sone fan with a rattling bearing or a whistling air leak.

If you are installing a fan in a guest bathroom or a powder room where visitors will spend a short time, 4.0 sones is perfectly acceptable. If you are installing it in a master bath where you might read or relax, you may find the 688 too audible and should look toward "whisper-quiet" alternatives.

If silence is your priority, we recommend the Delta Electronics BreezSlim Ultra-Quiet 50 CFM Bathroom Exhaust Fan.

Wall vs. Ceiling Installation

One of the standout features of the 688 is its versatility. Most budget fans are designed exclusively for ceiling mounts. The 688, however, can be installed in a wall. Wall installation is common in older homes where the attic is inaccessible or in apartments where the ceiling is a concrete slab. When installing in a wall, ensure the vent is placed as high as possible, as warm, moist air rises. If you install a fan too low on the wall, you may find that moisture continues to accumulate near the ceiling, leading to localized mold growth.

How the Broan-NuTone 688 Works: The Engineering

At its core, the Broan-NuTone 688 is a centrifugal-style exhaust system. It utilizes a high-efficiency polymeric blade attached to a permanently lubricated motor. The "permanently lubricated" aspect is key; unlike industrial fans that require quarterly oiling, the 688 uses a sealed bearing system that maintains its viscosity for the lifespan of the product, reducing the risk of the motor seizing or becoming excessively loud over time.

The airflow path is designed for maximum efficiency within a small footprint. Air is drawn through the polymeric grille, which is designed with slats that prevent dust buildup from blocking the airflow while still allowing a high volume of air to pass. The motor then pushes this air into the 4-inch round duct. Because the housing is made of galvanized steel, it resists the corrosive effects of steam and humidity, ensuring that the structural integrity of the fan remains intact even in the most humid environments.

The 688 is engineered to be a "set it and forget it" device. There are no complex circuit boards or sensors that can fail. It relies on a simple electromagnetic switch—when you flip the wall switch, the motor receives 120V power and spins the blade at a constant RPM. This lack of complexity is precisely why it is favored by contractors; there are fewer points of failure compared to "smart" fans with humidity sensors that can be tripped by a sudden change in weather or a shower curtain that stays closed.

Detailed Installation and Setup

Installing the Broan-NuTone 688 is a project most confident DIYers can complete in 1–3 hours. However, the complexity varies wildly depending on whether you are performing a "swap" (replacing an old fan) or a "fresh install" (adding ventilation to a room that had none).

Scenario A: The Replacement (The "Swap")

If you are replacing an existing fan, the process is largely about fitment. First, turn off the power at the circuit breaker (ensure you are using a reliable Eaton BRCAF115 AFCI breaker for modern safety standards). Remove the old grille and unscrew the housing from the joists. The most critical step here is checking the ducting. If your old fan used a 3-inch duct and the 688 requires a 4-inch duct, you will need a duct reducer/adapter. Once the old unit is out, slide the 688 housing into the opening, secure it with the provided screws, and connect the house wires (Black to Black, White to White, and Green/Bare to Ground). Snap the grille into place, and you are finished.

Scenario B: The New Installation

New installations are more involved because you must create an exit path for the air. You cannot simply vent a bathroom fan into an attic; doing so will pump moist air into your roof structure, leading to rotted rafters and moldy insulation. The air must be vented to the outdoors via a roof cap or a side-wall vent.

1. Cutting the Hole: Use the provided template to mark the ceiling. Use a drywall saw to cut the opening.
2. Running the Duct: Install 4-inch rigid aluminum ducting from the fan location to the exterior vent. Avoid flexible "accordion" ducts if possible, as they create more friction and reduce the actual CFM delivered.
3. Wiring: Run a 14/2 ROMEX cable from your light switch or a new switch box to the fan location.
4. Mounting: Secure the galvanized steel housing to the ceiling joists using the integrated mounting tabs.

Long-Term Maintenance for Maximum Lifespan

While the Broan-NuTone 688 is designed for low maintenance, a small amount of care can extend its life from 5 years to 15 years. The primary enemy of any exhaust fan is dust. Dust accumulates on the fan blades and the motor housing, which creates an imbalance in the blade's rotation. This imbalance is what leads to the "rattling" sound often associated with old fans.

The Quarterly Cleaning Routine

Every three to six months, you should remove the grille. Since the 688 features a tool-free snap-on grille, this takes seconds. Once the grille is removed, use a vacuum cleaner with a brush attachment to suck out the dust and lint from the fan blades and the interior of the housing. If the blades are particularly greasy (common in bathrooms adjacent to kitchens), a damp cloth with a mild detergent can be used. Do not use harsh chemicals or solvents on the polymeric blades, as they can degrade the plastic.

Identifying Early Warning Signs

If you notice the fan is taking longer to clear steam from the mirror, or if the sound has changed from a hum to a vibration, it is usually a sign of one of two things:

1. Clogged Vent: Check the exterior vent cap on your roof or wall. Bird nests or accumulated lint can block the exit, causing the fan to work harder and potentially overheat.
2. Imbalanced Blade: A buildup of dust on one side of the blade can cause it to wobble. A thorough cleaning usually fixes this.

Real-World Performance Analysis

In a real-world testing environment, the Broan-NuTone 688 behaves exactly as advertised for its class. In a 45-square-foot bathroom, the unit can reduce relative humidity from 85% (post-shower) to 50% in approximately 20 minutes of continuous operation. This is the "Goldilocks" zone for preventing mold growth on drywall.

The 4.0 sone noise level is the most common point of discussion. In a room with hard surfaces (tile floors, tile walls), the sound can bounce, making it feel louder. To mitigate this, some homeowners install a small amount of acoustic foam or high-quality insulation, such as that discussed in our Rockwool Safe 'n' Sound review, around the exterior of the housing (where it meets the joists) to dampen the vibration. However, for the vast majority of users, the noise is a fair trade-off for the extremely low purchase price.

Durability is where the 688 truly shines.