Broan-NuTone 688 Bathroom Fan: The Complete Buying Guide

Broan-NuTone 688: A Detailed Look

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.

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.

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 equivalent to a normal conversation. 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.

The 688 is certified by HVI and complies with Energy Star standards when used correctly for its rated square footage. At roughly 4.0 amps and operating on a standard 120V circuit, it's 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. If your needs are simple and your bathroom is small, the 688 is difficult to beat at its price point.

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Who Should Buy the Broan-NuTone 688?

The 688 is squarely aimed at homeowners and renters dealing with small bathrooms — think powder rooms, half baths, or a 3/4 guest bathroom where the square footage is modest. If your bathroom is under 50 square feet, this fan will adequately handle moisture and odor control without any need to upsize. It's also an excellent choice for landlords and property managers who need a cost-effective, reliable replacement fan that tenants can use without complications.

DIY enthusiasts will appreciate that installation is genuinely straightforward. As long as you're comfortable working with basic electrical wiring and have attic or wall access for ducting, the 688 can be installed in an afternoon. Broan includes a wiring diagram and installation template in the box, and the fan connects to a standard 4-inch round duct — the most common size in residential construction.

On the other hand, if you're outfitting a master bathroom larger than 50 square feet, running a spa shower, or if noise is a primary concern, you'll want to look at higher-CFM or lower-sone options. Similarly, tech-forward buyers who want humidity sensors, Bluetooth speakers, or app connectivity should look elsewhere — the 688 is refreshingly analog.

Installation: What to Expect

Installing the Broan-NuTone 688 is a project most confident DIYers can complete in 1–3 hours depending on whether you're replacing an existing fan or installing fresh. For a replacement, the process is straightforward: turn off the breaker, remove the old fan, connect the existing duct and wiring to the 688 housing, secure it to the joist or wall box, snap on the grille, and restore power. Broan's included installation guide covers each step clearly.

New installations are more involved, primarily because you'll need to run a 4-inch duct to an exterior wall or roof cap. This is typically the most time-consuming part of any bathroom fan installation and may require cutting through drywall or accessing the attic. If you're not comfortable with that portion of the work, this is a good stopping point to bring in a handyman or electrician — the fan itself is easy; the ductwork is where complexity lives.

One installation note worth flagging: the 688 uses a 4-inch round duct connection. Some older homes use 3-inch or rectangular duct runs. If your existing ductwork doesn't match, you'll need a transition adapter before installation, which adds a minor cost and a step to the process. Check your existing duct size before ordering.

Real-World Performance

In practice, the 688 performs reliably for moisture and odor removal in appropriately sized bathrooms. Run it during and for 15–20 minutes after showering, and you'll find mirrors clear, surface moisture dissipates, and odors are efficiently exhausted. There's no staging or variable speed here — it's full power on or off, which keeps the mechanical design simple and durable.

The 4.0 sone noise level is the most common point of contention in user feedback. To put it in perspective: at 4.0 sones, the fan is audible and present but not disruptive for most people. It's similar to the sound level of a moderate rainfall or an office HVAC system. Users who previously had aging, rattling fans often describe the 688 as an upgrade in noise terms. However, buyers accustomed to premium 0.3–1.5 sone fans will notice the difference.

Long-term durability reports from owners are generally positive. The permanently lubricated motor resists the wear that causes older fans to develop rattles and reduced airflow over time. The galvanized steel housing resists corrosion, which matters in a high-humidity environment like a bathroom. At this price point, finding a fan with equivalent build quality is genuinely difficult.

Variants and Related Models to Consider

Broan-NuTone produces several variants on the 688 platform, with the most notable being the 688C (which adds a 7-watt night light) and the 690 series, which bumps airflow to 70 CFM for slightly larger bathrooms up to 65 square feet. If your bathroom is at the upper edge of the 688's range, the 690 series is worth the modest step up in price.

For buyers who want a significant performance upgrade, Broan's SP110 series and the widely praised Panasonic WhisperCeiling FV-11VQ5 offer dramatically lower sone ratings (0.3–1.5 sones) and higher CFM outputs, though at a substantially higher price. These are the logical next step for master bathrooms or buyers for whom noise is a dealbreaker.

How the 688 Compares

The table below puts the Broan-NuTone 688 in context alongside its closest variants and a premium alternative so you can calibrate your expectations clearly.

How We Evaluated the Broan-NuTone 688

Our evaluation framework for bathroom exhaust fans centers on five key criteria: airflow efficiency (CFM rating relative to intended room size), acoustic performance (sone rating and real-world noise character), build quality and durability (materials, motor type, and warranty coverage), installation practicality (DIY accessibility, mounting options, duct compatibility), and value proposition (price-to-performance ratio within its market segment).

For the 688 specifically, we cross-referenced HVI certification data, manufacturer specifications, long-term owner reviews across multiple retail platforms, and independent testing data from home improvement publications. We also consulted guidance from the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) for ventilation rate benchmarks.

We deliberately do not rate the 688 against premium smart fans or large-bathroom models, as doing so would be comparing fundamentally different product categories. Within its category — budget fans for small bathrooms — the 688 performs at or near the top, which is the basis for our recommendation.