Broan Wall Heaters: Field-Convertible Voltage, But Watch That Grille

Broan’s 120V wall heaters deliver solid supplemental heating with one standout feature — dual-voltage flexibility that lets electricians convert them in the field. Models 174 and 170 come factory wired at 120V but can be converted to 208V/240V, solving installation headaches when electrical service doesn’t match the original spec. The thermostat design, however, creates problems that show up consistently in customer reviews.

Voltage Flexibility and Real-World Coverage

The dual-voltage design matters more than the marketing suggests. Model 174 offers 750W or 1500W at 120V (factory wired), convertible to 208V/240V. Model 170 provides 500W or 1000W options at 120V, also convertible to 208V/240V. This flexibility means contractors don’t need separate inventory for different electrical configurations — one model handles multiple voltage scenarios.

Coverage breaks down simply:

• Model 170: 65-100 sq. ft.
• Model 174: 100-150 sq. ft.

Both models share 12” W x 14-19/64” H grilles with 3-3/4” housing depth, fitting standard 2x4 framing without special rough-in requirements.

Model	Wattage Options	Voltage	Coverage	BTU Output
170	500W, 1000W	120V (convertible to 208V/240V)	65-100 sq. ft.	3,413 BTU @ 120V (1000W)
174	750W, 1500W	120V (convertible to 208V/240V)	100-150 sq. ft.	5,120 BTU @ 120V (1500W)

The 9810WH offers a 1000W @ 120V (9A) alternative with a white polymeric heat-resistant grille instead of the metal grille design that causes problems on the 170/174 series.

The Grille Problem Nobody Talks About

Here’s what the spec sheets won’t tell you — the thermostat placement creates real operational issues. Model 174 earns just 3.7 stars from 32 reviews, with the grille design causing heat backflow to the sensor. Model 170 shows the same problem — thermal shut-off issues when the grille is attached.

The engineering flaw is straightforward. Heat rises from the unit, hits the metal grille, and radiates back toward the front-mounted thermostat sensor. The thermostat thinks the room is warmer than it actually is, cycling off prematurely. Some installers work around this by adjusting the grille mounting or adding insulation barriers, but that’s fixing Broan’s design problem on your dime.

Noise levels run higher than competitors — another consistent complaint across reviews. The permanently lubricated motor helps with maintenance-free operation, but it’s not particularly quiet.

Montana’s extreme temperature swings make thermostat accuracy critical. When it’s -20°F outside and you’re trying to keep pipes from freezing in a utility room, premature cycling isn’t just annoying — it’s a failure risk. The 9810WH’s polymeric grille design might avoid the heat reflection issue, though customer data on that model remains limited.

Installation Notes and Montana Considerations

Recessed mounting fits 2x4 framing. Surface mounting requires Model 84 kit — an extra purchase that adds cost and complexity. Factory wiring comes set for maximum wattage at 120V, requiring field conversion for other configurations.

For Montana’s varied electrical infrastructure, especially in rural areas running on different voltage systems, the field-conversion capability proves valuable. Older buildings might have 208V three-phase service, while newer construction typically runs 240V single-phase. One heater model handles both scenarios.

Both models are compatible with Broan’s 87W Line Voltage Wall Thermostat if you want remote temperature control instead of the problematic built-in thermostat. Given the sensor location issues, external thermostat control might deliver better performance.

The 20-gauge steel construction with white enamel finish holds up fine in bathroom moisture environments. The rapid warm-up alloy heating element delivers heat quickly — important when you’re stepping out of the shower on a January morning.

FAQ

Can these heaters handle Montana’s cold extremes as primary heat sources? No. These are supplemental heaters designed for small spaces. Model 174 covers 100-150 sq. ft. and Model 170 handles 65-100 sq. ft. They work for bathroom warmth or freeze protection in utility closets, not heating entire rooms through winter.

What’s causing the thermostat cycling problems? The grille design causes heat backflow to the sensor. Metal grilles radiate heat back toward the front-mounted thermostat, triggering premature shut-off. Installing an external thermostat bypasses this design flaw.

Is the surface mount kit needed for new construction? Not typically. Recessed mounting fits standard 2x4 framing. The Model 84 surface mount kit is mainly for retrofit installations where you can’t cut into the wall.

Which model works for a standard 5x8 bathroom? Model 170 (65-100 sq. ft. coverage) handles a 40 sq. ft. bathroom fine. Run it at the 1000W setting for faster warm-up on cold mornings.

Are these heaters actually UL listed? Yes, both Model 174 and 170 carry UL listing. They include 1-year limited manufacturer warranty coverage.