LittleJoeMuchttps://write.tchncs.de/@/LittleJoeMuc/atom.xml2021-01-22T23:24:48.011509+00:00<![CDATA[Monitor my heating system]]>https://write.tchncs.de/~/JoeFunkt/monitor-my-heating-system/2021-01-22T23:24:48.011509+00:00LittleJoeMuchttps://write.tchncs.de/@/LittleJoeMuc/2021-01-22T23:24:48.011509+00:00<![CDATA[<p><img src="https://write.tchncs.de/static/media/DA37619D-D24A-FAA4-F63A-28F8065878F8.png" alt="Ein sensor im Heizungsraum und eine Grafik des Temperaturverlaufs">
A few weeks ago my heating system broke.
I noticed this - well because it got pretty cold at home. So I thought it would be really nice to get an early notification e.g. via mail, if the temperature of the heating boiler drops below the normal temperature. So I would have some buffer time to call the heating technician or check the heating myself, before the whole house is cold.
I´m sure I could have bought something proprietary from the heating system manufacturer, but building an TTN sensor would be a lot cheaper - and it´s fun! :D</p>
<p>I wanted to use hardware I already had lying around, this was:</p>
<ul>
<li>Adafruit Feather 32u4 LoRa board</li>
<li>100k ntc resistor</li>
<li>2000 mAh LiPo</li>
</ul>
<p><img src="https://write.tchncs.de/static/media/0A2DBBAE-8CFF-9197-E465-59852AB34555.jpg" alt="Sensornode ohne Batterie und Gehäuse"></p>
<p>I couldn´t find a fitting formula to convert the analog read input values of the ntc to temperature, so I did A LOT of measuring the analog inputs, while attaching the ntc to hot and cold things. XD
And with some help of Excel I got a formula which is actually pretty good.</p>
<p><img src="https://write.tchncs.de/static/media/99CCDF6C-9FD3-6CCB-62A3-46CB08350983.png" alt="temperaturkurve excel"></p>
<p>Putting together the hardware and printing an enclosure was the easier part. Adafruit published some variations for printable feather cases. I just modified it a bit for my needs and made a custom wall mount.</p>
<p><img src="https://write.tchncs.de/static/media/252F92DB-8DFA-54AB-6246-E9B9F3EB6B91.jpg" alt="Sensor fertig und montiert"></p>
<p>For visualizing the temperature, I´m using NodeRED.</p>
<p>Next step for me was battery testing. With measuring and sending the LoRa packet every 20 minutes, the device only lasts for 8 days. This was not very surprising because I did not use any sleep library so far.
So I installed the Adafruit Sleepydog library. Now it is running for 10 days and the battery voltage is still very good. I think it could last about 6 to 8 weeks now, until I have to recharge it. (which is pretty simple with feather boards, just plug a powerbank in the USB port)</p>
<p><img src="https://write.tchncs.de/static/media/565AF539-23DA-2E27-932E-38A217D135C1.png" alt="Grafik Temperaturverlauf"></p>
<p>What´s still left to do, is to program the email notification, but that’s also very easy in NodeRed. 😊
You can see the process of the designing in full detail (in german) in this Mastodon thread: https://social.tchncs.de/<a href="//write.tchncs.de/@/LittleJoeMuc/" title="LittleJoeMuc" rel="noopener noreferrer">@LittleJoeMuc</a>/105304013699179714</p>
]]>