Tapo H100: Cellar Humidity Monitoring in Home Assistant

Cellars sweat. On a warm humid day the air you let in is warmer than the cold concrete, and the moment it touches a cold surface it gives up its water. That's condensation, and over enough summers it's how a basement grows mould in the corners you never look at. I wanted a number that warned me before that happened. The catch I already knew going in: a raw relative-humidity reading isn't that number. This is Part 08 of the series. The hub was already in the house running other things, and the install was genuinely the easy 20 minutes. The part worth writing about is what came after the sensor showed up: turning its two raw readings into a dew-point spread, and deciding when that spread means "act" versus "ignore the spike." Why the H100, and why 868 MHz is the whole point The hub is a TP-Link Tapo H100 , a little smart hub that acts as a radio bridge for TP-Link's battery sensors — the T100 motion, the T110 contact, and the one I care about here, the T310 temperature/humidity sensor. Here's the load-bearing detail, and the reason I reached for this hub instead of a WiFi sensor: the Tapo sensors don't talk WiFi. They talk to the H100 over 868 MHz sub-GHz radio . That matters in a cellar more than anywhere else. Sub-GHz is long-range and punches through concrete and floors in a way 2.4 GHz WiFi simply doesn't. There's no WiFi worth having down in my cellar, and no interest in running a repeater into a damp room just to read a sensor. The T310 sits down there on a battery, the H100 upstairs where the network is, and the radio link between does the work. One H100 supports up to 64 sensors — for a house, more headroom than I'll ever use. Getting the sensors into Home Assistant The native TP-Link integration doesn't expose the H100's child sensors — it's built for the plugs and bulbs. The one that works is the community Tapo Controller integration (petretiandrea's TP-Link Tapo ), installed through HACS , the same custom-integration store I've leaned on throughout this ser