As homes are designed and built to be more air tight, mechanical ventilation becomes a necessity. Once a bastion of high-performance green homes, mechanical ventilation systems have made their way into the spec sheets for many production builders. But even in homes with whole-house automated ventilation systems that constantly supply the structure with a flow of fresh air, the bath is often equipped with simple on-off switch for control of the overhead exhaust fan. These fans are critical to maintaining interior air quality as they are designed to evacuate the mass of humid air that ensues as the shower is used or the bath tub is filled.
Reducing the humidity in your bath is one of the best ways to help prevent the formation of mold—a decidedly unhealthy proposition—and that is where fans come in. And one of the best ways to operate your bath fan for the recommended 30 minutes is by retrofitting the wall switch to a digital timer, a nice upgrade over the twist-to-set mechanical fan timers that are widely available. There are many choices here, but we have found one of the best solutions to be the Eaton Aspire 5-Button Preset Timer Switch (item number 9590), a roughly-$27 digital timer equipped with 5 simple preset buttons to run the fan for 5, 10, 15, 30, or 60 minutes. This switch is easy to install in most homes, and its 15-amp, 1800-watt capacity will work with most standard overhead bath fans rated up to 1/4 horsepower. This is a non-smart switch, meaning you cannot connect it to home automation system or control it with a voice activation command. There may be some smart switches available here, but they may be overkill for this application. Also be aware many digital in-wall timer switches are designed strictly for lighting and are not compatible with fan motors, so be sure to double-check the specs of any timer before buying.