<story><title>DiyPresso: DIY Espresso Machine</title><url>https://www.diypresso.com/</url></story><parent_chain><item><author>ManDeJan</author><text>A neat project for sure but as it stands this has major safety issues. The control logic is able to lock up and keep the boilers heating element in an forever &amp;quot;on&amp;quot; state till something snaps. I couldn&amp;#x27;t find a mention of safety in the manual nor see any mechanical safety failsafes in case of overheating.</text></item></parent_chain><comment><author>michaelt</author><text>&lt;i&gt;&amp;gt; I couldn&amp;#x27;t [...] see any mechanical safety failsafes in case of overheating.&lt;/i&gt;&lt;p&gt;On the assembly instructions, page 39 shows the boiler assembly has a therm-o-disc thermostat fixed to the top. It&amp;#x27;s not labelled, you just have to recognise it. The schematic on page 44 shows it&amp;#x27;s wired in series with the boiler&amp;#x27;s heater. That provides redundancy for the main temperature control, which is presumably the microcontroller sensing from the PT1000&lt;p&gt;Page 32 also describes the installation of an overpressure valve (which appears to return water to the cold tank?)&lt;p&gt;The machine does lack hardware run-dry protection though; as far as I can tell, it relies on a load cell to detect if there&amp;#x27;s water in the tank. If you ran it without water to conduct heat from the heating element to the thermostat, the thermostat wouldn&amp;#x27;t function. So it&amp;#x27;s not entirely safe, as you say.&lt;p&gt;[1] &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;diypresso.com&amp;#x2F;wp-content&amp;#x2F;uploads&amp;#x2F;2024&amp;#x2F;05&amp;#x2F;2024-05-27-manual_diyPresso_One.pdf&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;diypresso.com&amp;#x2F;wp-content&amp;#x2F;uploads&amp;#x2F;2024&amp;#x2F;05&amp;#x2F;2024-05-27-...&lt;/a&gt;</text></comment>
<story><title>DiyPresso: DIY Espresso Machine</title><url>https://www.diypresso.com/</url></story><parent_chain><item><author>ManDeJan</author><text>A neat project for sure but as it stands this has major safety issues. The control logic is able to lock up and keep the boilers heating element in an forever &amp;quot;on&amp;quot; state till something snaps. I couldn&amp;#x27;t find a mention of safety in the manual nor see any mechanical safety failsafes in case of overheating.</text></item></parent_chain><comment><author>nabilhat</author><text>A thermal fuse isn&amp;#x27;t for overpressure control, it&amp;#x27;s intended to trip before a physical overpressure control vents superheated steam. Both provide failover redundancy independent of operational heater controls.&lt;p&gt;There isn&amp;#x27;t enough detail of the boiler to tell if there&amp;#x27;s an overpressure relief valve. The boiler can&amp;#x27;t be made safe without one. If they&amp;#x27;re cheap enough to be standard in cheap knockoff moka pots one should be here...&lt;p&gt;This machine&amp;#x27;s wiring diagram shows an unlabelled shape wired in series with what might possibly be the heating element and a shape with &amp;quot;ssr&amp;quot; in its label. Which places the first unlabelled shape in the right place to be a thermal fuse or switch. If they&amp;#x27;re cheap enough to be standard in Mr Coffee machines one should be here...&lt;p&gt;Safety discussion in this project is conspicuously absent. Knowledgable users shouldn&amp;#x27;t be making assumptions like this about safety features. Assumptions and safety aren&amp;#x27;t compatible. Average users should be informed in detail about the safety features they&amp;#x27;re tasked with assembling.</text></comment>