Will a Kettle Full Of Alcohol Stay On Forever?

I still don't understand the design of the white kettle. Help me! Also, I still don't know why the 40:60 vodka boiled for longer than either water on ethanol on its own. Something to do with heat capacity maybe. The sponsor is Curiosity Stream: Get a whole year for just $14.99 curiositystream.com/stevemould

This demonstrates exactly why forming a hypothesis and then doing the experiment is so important. I was just as confident as you were what the likely results would be, and was equally as wrong. Looking at the length of the video, I knew there must be a catch, but without that context, I would have been just as surprised!

I love that what was initially a physics/chemistry experiment turned into a deep dive into kettleology.

They say admitting that you're wrong about something is hard, but this video shows it's actually super easy, barely an inconvenience!

sad to see he wasn't doing multiple "taste tests", would be fun to see a progressively more hammered steve mould do science.

the thermal contact must be for emergency thermal runaway. When the kettle is dry that heating element will melt itself and the kettle. No way those plastic parts would hold up. Must use the steam as the primary, and the contact one for runaway. This finally makes sense why my kettle wouldn't shut off on it's own with the lid open a crack. I'd been wondering that for years!

I used to work for Salter, and assessed a lot of kettles similar to these. The secondary thermostat is indeed a safety failsafe, to prevent a fire in case the primary temperature controlling thermostat does not activate - it's typically set slightly above the normal operating temperature range, so it would only switch if the kettle is heating up uncontrollably. Inclusion of these failsafes is a requirement of the Low Voltage Directive - if you're curious, the standard EN 60335 goes in to some detail about what's required.

This is why you need teams of full-time engineers to make stuff like kettles.

I wish more videos were like this on YouTube. Seeing the thought process and “failures” in understanding the construction is really quite pedagogic. The absolute best way to teach your audience. Great job my good sir. Hoping for more videos like this. Also takes courage to admit your hypothesis was wrong

So here's a fun one: If you've ever seen one of those rice cookers that only has a single switch that pops up when the rice is done, those DO work the way you've hypothesized. The difference there is they're set above 100 C. When all the water has either been absorbed or evaporated, the temperature is allowed to rise above that mark, and turn off the cooker via * a similar system using the curie point of a magnet, where the magnet will temporarily lose its magnet properties releasing the switch *. * edited *

The sensor with the thermal grease is called a resettable thermal fuse or thermal cutout switch. They are used for safety reasons for when a heating element/control circuit goes out of control. They usually have quite a high temperature rating before they switch, and don't have a very good cycle life (you wouldn't want to rely on it switching every day in a product). You can find exactly the same style ones in things like space heaters, microwaves, etc.

I do think the thermocoupled sensor is for boil dry protection, try boiling that kettled with the lid open until empty and see if it switches off. The temperature setpoint for that is probably well above 100°, something that would only be hit with no thermal mass being heated

This was definitely the most interesting video I've seen on kettles! Fun to watch you do trial and error and come to conclusions. Subscribed!

seeing someone say "damn, damn, i was wrong" with a huge smile on their face is so goddamned wholesome

I recently turned my kettle on and went to the bathroom, expecting it to turn off. When I came back it was still on and there was a strong burning smell. I went to turn it off and almost burned my finger on the switch. So I bought a new kettle. That's my anti-climactic story of the day.

6:40 I've actually been using a kettle like that for several years, initially at about 5200 ft above sea level before moving closer to the coast. It was programmable to several temperatures, intended for different teas (e.g. 175°F for green tea, 190°F for herbal teas, 200+°F for black teas). I quickly found out that yes, it would boil dry if set to 212°F at that elevation, and 200°F worked a lot better for me, being a lot closer to boiling at that altitude. From the very start of the video I was saying to myself, "It depends on the kettle's shutoff mechanism..."

The "bimetallic" disc is usually shape memory metal these days. It has a snappier toggling action and works at a dependable temperature based on the exact alloy. The glass kettle probably has an extra one (or even 2 for extra safety, like mine) buried under the switch mechanism for the safety boil-dry cutoff, and maybe the white kettle has it's main sensor in the handle so is functionally identical to the glass one.

10:00: Easy answer: A few years ago, someone accidentally triggered the lever of the water cooker at my workplace. They didn't notice that, and the water cooker was turned on, without water inside. Apparently, that cooker didn't have the thermal coupling to the base and instead only relied on the steam. But if there's no water in there, there is no steam in it either. We noticed only a few hours later, when someone noticed the smell coming from the kitchen. Long story short: This cooker hat started to melt already and we were quite lucky that someone noticed it before everyone left the office that day.

I remember being a line cook, and sometimes people would want their soup even hotter than the temp we held it at. So I'd throw some in a pan and swirl it over heat until the soup boiled. I would always then say "well, it can't get any hotter than that" and so many people greeted that response with a confused look. It was weird, because it was always my assumption that boiling was as hot as a liquid could get (and all energy input thereafter went into the phase transition). Thanks for another great video steve.

Thanks, I've always wondered how these work and enjoyed following along on this one!