Half a croissant, on a plate, with a sign in front of it saying '50c'
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DIY Induction Shower Heater

If You Die It's Not My Fault
  [vote for,

The instructions for the simplest, cheapest and possibly most unsafe DIY Induction Shower Heater™ are as follows:

1. Screw a portable induction stove sideways to a wall, well away from where water can splash upon it.

2. Take an induction-rated pressure cooker. In place of the regulator valve, bore a hole. To this hole affix the water inlet hose.

3. Bore another hole on the pressure cooker's wall, and to this hole affix the water outlet hose to which the showerhead attaches.

4. Mount the pressure cooker onto the induction stove with the outlet pointing downward. Anchor the pot to the stove with some degree of creativity. A frame perhaps. But definitely not adhesive.

5. Voila. After use, DO NOT FORGET to switch it off.

mailtosalonga, Sep 29 2021

(?) Heat Wayv microwave domestic water heater
grr... bad... snakeoil... [Frankx, Sep 29 2021]

Heat pumps https://www.theheat...s-/-central-heating
With hot water, under-floor heating, & radiators. [neutrinos_shadow, Sep 29 2021]

heat wayv microwave boilers https://www.boilerg...v-microwave-boilers
Fixed link for article on "grr... bad... snakeoil..." heater [a1, Oct 26 2022]


       //In place of the regulator valve, bore a hole.//   

pertinax, Sep 29 2021

       OK, I have questions:   

       The regulator valve would normally be in the top of the pressure cooker, where the steam comes out when necessary - right? And yet, you're turning this into in inlet port, while your outlet port is further down the pot - why?   

       Since you have two holes in the pot, you're no longer regulating its pressure. It's now just a pot - unless ... the heat is, by implication, coming from the portable induction stove, but are you adding further heat with a heating element built into the pressure cooker?   

       So, now you're powering two heating elements, one inside the pot, the other one outside. But a pressure cooker with its own heating element, unlike a normal stove-top pot, is designed to have insulating walls, not conducting walls, isn't it? So, the induction stove is acting mostly as a shelf-cum-space-heater, and contributing little to the heating of the water. So, are you living in a very cold climate, where your shower cubicle needs its own space heater?
pertinax, Sep 29 2021

       Hey I have a cheaper one. 1. fix a parrafin blowtorch to spout of galvanised watering can using duct tape. 2. Light blowtorch and fill can with water. 3. Hold contraption above head and pour.   

       Anyone want to step up another rung?
pocmloc, Sep 29 2021

       This reminds me of microwave water heating - it's possible to heat water for your home more efficiently than any other method by focussing microwaves on water flowing through a plastic pipe. Because the pipe diameter and flow rate are known, the microwave emitter can be optimised. Microwave home heating systems are now in development, I think.
hippo, Sep 29 2021

       I don't get it. If you convert, say, 1kJ electrical energy into thermal energy in water, you get 1kJ heat in your water. A normal resistance heater will achieve 100% efficiency - why use induction or microwaves?   

       I suppose you can dynamically adjust the power (heat input to your water) more finely with a microwave heater - but that works out the same as using a thermostat shower mixer (in terms of total energy).   

       I kind of like the dangerous DIY version in the original idea. [+]
Frankx, Sep 29 2021

       //Microwave home heating systems are now in development,//   

       What? I invented that when I was about 12, my brother thought it was a good idea and I was presented to a family friend - a physicist working in reactor design - to explain. He gave a little chuckle and said "a complicated way of solving a perfectly solved problem! There's plenty of careers in that. If you water-cool the transformers, you'll actually get within 10% of a normal heater".   

       //A normal resistance heater will achieve 100% efficiency - why use induction or microwave// Hence the chuckle. At least my idea used the pipes to guide the microwaves around a house.   

       //heating element doesn't have to be in immersed in the water. A common failure mode of home water heaters is scale or corrosion building up on the heating elements.//   

       The problem isn't because of the heating element being IN the water, necessarily. The scale derives from the peculiar way in which carbonates etc. become LESS soluble in water as temperature rises. You could heat the water in any way you like and scale will still form.   

       There are other problems with corrosion caused by dissimilar metals and so on which is why water heaters usually have a sacrificial anode (which no one ever replaces).
bs0u0155, Sep 29 2021

       //I suppose you can dynamically adjust the power (heat input to your water) more finely with a microwave heater//   

       Microwave or induction, presumably. The microwave we all use to heat our lunch is an example of a relatively high-power commercial product, a water heater would likely be a scale up of that. If it's anything to go by, it has dreadful fine control. 50% power is just on for 5s, off for 5s. The only induction stove I used was similar, but maybe in 0.5s pulses.   

       I have a heater that is astonishingly precise, it's used to heat the 100x objective on one of my microscopes, that's just a little flexible Kapton-insulated resistive heating element. The key to precision, accuracy & most importantly, stability, is careful control which we get from multiple thermistors and a PID controller which varies Voltage and pulse frequency.   

       Getting fine control of heating is so easy with large tanks of water, water has such thermal capacity & conductivity that you barely have to try to keep it stable. My 50W aquarium heater is set at 24C, it's on for hours at a time before the controller decides the temperature is raised enough based on the sensor at the other end of the tank.
bs0u0155, Sep 29 2021

       Good find [a1] with the heatwayv microwave boiler.   

       Some really dubious text about the technology in the FAQ section of their website:   

       Of conventional immersion heaters:   

       "there is dissipated volumetric loss that directly affects thermal efficiency which has to be taken into consideration when evaluating overall performance. This thermal loss equates to 1% per radial centimetre from the element during its heating phase and once temperature is attained 03% loss per radial centimetre during its stand-by reheating phase. Accordingly, an immersion coil situated in a tank with a diameter of 450mm (R225mm) would be just over 75% efficient during the high-energy consuming heating phase"   

       Of their microwave heater:   

       "it fully maximises current resistance in signal generation and amplification by utilising convected waste heat to elevate the initial water temperature. Secondly, 100% of the generated microwave signal is transferred into the liquid via confined cavities and highly dielectric materials to reach nominal thermal temperature. Finally, optimal usage temperature is attained and maintained by latent heat transfer into the liquid through the use of proprietary exothermic diffusing insulation."
Frankx, Sep 29 2021

       //really dubious text//   

       A steaming pile of horseshit is what that is.   

       There will be an engineer on staff, and they were likely... motivated.. to come up with that. Poor chap probably hasn't slept since.   

       From their front page:   

       "Heat pumps are expensive to purchase, are cumbersome to retrofit requiring the replacement of incumbent heating systems such as radiators, less responsive in “on- demand” operation"   

       A huge fridge compressor is no more expensive than a huge microwave that they're proposing. At least a heat pump can run on a normal domestic power supply. A whole-house hot water + heating sized microwave water heater would definitely require some serious thought on the electrical supply side. I don't see why a heat pump couldn't run with radiators and I don't see why it would be less responsive.
bs0u0155, Sep 29 2021

       [bs0u0155]; heat pumps with radiators are definitely a Thing. See linky.
neutrinos_shadow, Sep 29 2021

       //You could heat the water in any way you like and scale will still form. //   

       More easily and cheaply fixed with a microwave heater. Just swap out a short length of pipe.
Voice, Oct 26 2022


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