[alex3305]

No worries. I am glad to answer your questions.

First of all, I'm also concerned by legionella growth. However all the sources I can find suggests that at a legionella run above 60 degrees celsius once a week should be enough to kill all bacteria. So that's what I'm doing.

My sensor installation was extremely easy. My warm water heater is in fact a barrel within a barrel. And some insulation material between those barrels. If it would only be metal, you lose too much heat. In the outside barrel (excuse me for lack of a better term) there was an analogue thermometer. This thermometer has a metal back so it makes direct contact with the inside barrel. I just pulled this one out and replaced it with a DS18B20 probe. Again metal against metal, so maximum contact.

Finally I have calibrated the sensor by running it with hot water at the tap and measuring the temperature both there and on the warm water heater (with 2 DS18B20). I've done this for several temperatures with intervals of 10 degrees. I've ignored possible sensor deviations. Finally I used Excel's INTERCEPT and SLOPE functions on the range to calculate the value needed for a linear equation. I have used the formula:

    boiler_temperature * SLOPE + INTERCEPT

My math is probably far from perfect and I might revisit it one day. But it works for me currently. I also visualized the measurement results with my calculations and they seem to be pretty accurate. Especially when accounting for missing measurements.

I've also added my personal page to the 'About me' on here, and I have the same Reddit username if you want to DM me there.