Smart Humidity Climate Control (Multi-Device with Manual Override)
What It Does
Humidity control for Home Assistant that handles the real world. At its core it turns devices on when humidity rises and off when it drops — but it goes further:
- Uses temperature-corrected humidity math (Magnus-Tetens) to eliminate false triggers from room-to-room temperature differences — configured in familiar percentage (%) rather than absolute water mass units
- Detects manual overrides and respects them — backs off when you touch a device and waits a configurable window before taking back control, no tug-of-war
- Protects equipment with a configurable safety watchdog that force-stops devices if they run too long, followed by a dedicated rest period to let equipment recover
- Separate turn-on and turn-off thresholds prevent rapid on/off cycling when humidity hovers near a trigger point
- Controls multiple devices as a unified group with shared lockout logic — touch any one device and the whole group suspends automation cleanly until the manual override timer expires
- Gracefully handles sensor failures with configurable fallback modes
No more automation fighting you for control of your own devices. No more fans running all day because a sensor went offline. Put it all together and you get humidity control that works quietly in the background, responds intelligently when you need to intervene, and protects your equipment along the way — without you ever having to think about it again.
Features
- Thermodynamic Normalization — Magnus-Tetens formula corrects reference humidity to the primary room’s temperature, eliminating false triggers from room-to-room temperature differences
- Manual Override Detection — Detects who changed a device via HA’s context system; any manual touch pauses the entire group for a configurable cooldown — no tug-of-war
- Two Independent Timers — Safety Rest Period and Manual Override Cooldown are fully separate; tune each for your specific needs
- Safety Max Run Watchdog — Force-stops devices after a configurable maximum run time to protect equipment from sensor failures or open windows
- Two-Track Max Run Timer — Automation-activated and manually-activated devices use separate max run calculations so the watchdog always fires at the right time
- Smart Safety Rest Loop — Handles manual touches during a rest period gracefully, keeping both timers honest
- Multi-Device Support — Fans, switches, lights, input booleans, or helper groups; all act as a unified team with shared lockout logic
- Per-Device Recovery — After any lockout expires, each device is individually reclaimed so a manually-toggled device is correctly recovered even if others were unaffected
- Direction-Aware Hysteresis — Separate rising and falling thresholds prevent rapid cycling
- Dynamic Fail-Safe — Falls back to a Static Baseline slider or Raw RH% comparison if reference sensors go offline
- Automatic Unit Conversion — Handles mixed °C/°F sensor hardware transparently
Requirements
- Primary humidity sensor
- Control Device (fan, dehumidifier, etc)
- Primary temperature sensor, reference humidity sensor, reference temperature sensor (all optional, but needed for full thermodynamic normalization)
Known Limitations
- Effective run time: Due to HA’s minute-tick polling, devices run for approximately
max_run + 1minutes per cycle. Set values accordingly. - Sensor response lag: Temperature and reference humidity sensor changes may take up to 60 seconds to affect behavior. Primary humidity sensor changes are always instant.
- Sensor accuracy: Consumer humidity sensors carry ±2–3% tolerance. Two sensors measuring the same air can read 4–6% apart. Avoid thresholds tighter than your sensors’ combined accuracy.
- Manual override detection: Relies on HA’s context system. Some voice assistants and third-party integrations may not correctly identify manual changes, bypassing the lockout.
- HA restart during Safety Rest: The rest timer is lost on restart. Devices may re-activate before the full rest period has elapsed.
- Device flicker: Devices may briefly turn off then immediately back on during transitions out of manual override periods. This is intentional — the automation clears stale user contexts before reclaiming devices to ensure timer logic stays accurate.
- Helper Group tip: If using a Helper Group, “All Entities” OFF mode is recommended — “All Entities” ON can cause partial manual-ON states to go undetected by the lockout.
Credits
Based on [Switch a fan based on absolute humidity difference between two humid/temp sensors] by W6Es3QEa. Substantially rewritten with multi-device support, manual override intelligence, safety watchdog, independent timer architecture, per-device drift detection and modern Home Assistant standards.