Earlier post 'Iot for swimming pools' I created water-resistant thermometer for my swimming pool. Now it's time to create thermometer with same parts for my sauna. The cables with DS18B20 sensors are capable of withstanding temperature range -55C to +125C. Maximum temperatures in sauna can reach +110C depending of what meter you are using ( and who is measuring...), so DS18B20 should do well.
I created the sensor like I did with swimming pool sensor. Nothing new in there. The Fibaro sensor is not rated for high temperatures so it's outside of sauna and the cables go inside the sauna. I did not insert the cables through the walls but just from the doorway near the floor where there's no door because of free air flow. Next time I'll renovate sauna, I'll do the inserts through the wall.
I chose not to hide the sensors, because it's not possible. They need to have good contact to moving hot air. The sensor's cables go inside a heat treated aspen. The color of heat treated aspen is more brown that the walls, so it will be visible and it was a conscious choice for it to stand out a bit.
First I made three channels for the sensors in the back with a milling machine. There are two parts, one for above the benches (the one with sensors sticking out) and one for below the benches to hide the sensor cables.
This is the normal lighting in sauna, very dim, and it shows the sensors don't stand out too much.
Here's the temperatures of one sauna visit.
I have a wood burning stove (kiuas) in my sauna and have to add more wood every 25 minutes. You can actually see two times I did that when warming up the sauna. You can also see how many times I opened the door and went in and out for cooling. The temperatures are little lower than in thermometer on the wall but I'm not competing about how high temps I can tolerate. I don't know which one shows the 'right' temperature.
Right now I can see from my home automation system, when I have to go add more wood but I've so used using wood burning stove so I don't necessarily need it. I just know when I have to do it. But I can automate my system to understand that I'm having a sauna and set automatically also my swimming pool to 'swimming' mode and my yard IR heater to standby mode waiting for movement from motion detectors. I can also set it to send a notification 'Sauna is ready' when temperature reaches 80C and of course also set fire alarm if temperature rises above 120C. When temperature goes down below certain point, it set's the 'sauna' mode off which in turn sets 'swimming' mode off and stops IR heater's standby.
There is not much of use this data for statistics and data analysis but a nice addition to further automate my home.
I love it!
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