Santiago Lema Jun 9
Preparing #ESPHome controller for that sauna project with LED buttons and a small LCD screen.

It’ll be accessible from #HomeAssistant for stats & alerts mainly but fully independent.

Obviously with that kind of electric heater load (once connected to the contact or, not pictured ) that’s not the kind of thing you want to depend on a working (or not) WiFi.
Show threadSantiago Lema Jun 9
For what it’s worth I got this SHT-40 sensor from Ali that comes wide a protective cover. Hopefully it’ll resist the harsh conditions (max 85°C as I have moderate tastes in self-body cooking).

https://a.aliexpress.com/_mrvQoeb

I tested it with my small Hot Air rework station. At least I actually used it for once…

So far the sensor appears to work pretty well but only time will tell.
SHT40 SHT30 SHT20 SHTC3 Temperature Humidity Sensor Module Probe Cable Waterproof Digital Capacitance Sensors 1M I2C Output - AliExpress 502

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Show threadIlkka Tengvall
@santi how do you make sure the sauna stolve shuts down even if software bugs? I was just thinking of such yesterday, and thought there should be some sort of watchdog timer in relay box that shuts it down if no control mesage received in given time.
Jun 10 at 7:37pmWeb
Show threadSantiago Lema 6d ago
@ikkeT@mementomori.social @santi #ESPhome is much more reliable than say depending on remote Home Assistant but I have seen ESP32 lock up if you input the wrong current from a sensor on GPIO for example. Would be bad.

I am planning on adding another ESP at the root with an energy sensor on the wire and a maximum timer.

Of course the simplest/safest way would be to just turn off the dedicated circuit breaker when not using it (the controller of course is on a separate circuit with an UPS).
Show threadSantiago Lema 6d ago
@ikkeT@mementomori.social @santi I also have power monitoring at the house level. That kind of drain (6500w!) won’t go unnoticed long.

But energy usage isn’t the worst. Infinitely heating could damage things. I am not sure yet what the exact maximum temperature this could get too if let on forever. There are holes for vent of course on the sides and also a large exaustor in the base I can turn on to drain out the hot air.
Show threadSantiago Lema 6d ago
@ikkeT@mementomori.social @santi I plan the program to allow max 85° and of course turn off if sensor isn’t responding. Real risk is ESP32 / relay locking up. That is a very rare event though. Only case I saw this happen was a homemade solar system with out of range values going back to the sensor.

Still doesn’t hurt to plan ! I’ll definitely physically turn off the breaker when away.