I’m automating my bathroom fan… again. Earlier this year I built a “pricey-but-perfect” setup using the Inovelli fan switch plus an Arre temperature/humidity sensor placed right above the shower, and it worked great—until the seasons changed. My Apple Home automation was based on fixed humidity thresholds, so my baseline humidity drifted from ~40% to the mid-40s and beyond, which caused random fan triggers… then eventually the fan never turned on because the house was already sitting above my threshold. Add in a dead sensor battery for weeks, and it was time to rethink the whole approach. In this video I rebuild the logic around what’s always true during a shower: humidity rises fast. Instead of “turn on at 55%,” I use rapid-rise logic (like +8% in 3 minutes) and build it in Homey Pro using Advanced Flow and a couple variables. Then I swap in Inovelli’s new White Series Matter-over-Thread on/off switch with built-in humidity sensing to get to a single-device solution—no extra sensor, no batteries. The catch: the humidity data is noticeably jaggier than the Arre sensor, so I show how I refined the automation (including adding a “lights must be on” condition), and I share an Apple Home workaround using a threshold plus a short “wait and re-check” Shortcut to avoid false triggers.