Peter Davey Heater

[EMdevices]

I'm no expert on the resistive properties of water and how they vary with Temperature, Salt content, other ions, turbulence, etc..,  but it also surprises me a bit that there seems to be a higher current draw once boiling set in.  Considering just a simple model of resistance that depends on the surface area (and other factors of course, like spacing of the plates, etc..)  the presence of bubbles would indicate less electrode surface exposed to the conductive water, so resistance should be higher (assuming the hot steam filled bubles are not more conductive than water) however this does not seem to be the case from Sprocket's experiment, and we can speculate quite a bit why it's not, but I suspect we can find an answer in the scientific literature as I'm sure others have done carefull research into boiling. 

Years ago I was invovled (for a short while) with microgravity research.  We would drop an experiment from a great height (a few stories) and while it was in free fall , hence microgravity, we would run the experiment which consisted of boiling water and filming it with video cameras mounted on the experiment and recording everything.   I believe later on they got this experiment to fly on the space shuttle.    So anyway, I'm sure lots of scientists have investigated boiling and I'm quite sure this same type of boiling, utilizing the conduction properties of water, has been looked at.  Perhaps somebody with a membership at ASME or other engineering organization can do a search and see what comes up.

Anyway, even if these heaters are no OU, I would still like to build a small contraption like this Davey heater so I can heat up the water in a glass or cup and make tea or other hot drink with minimum heat loss.   Microwaves are efficient, but some people have doubts about the health benefits (not me), and heating up water on a stove top is wastefull as you're leaking heat all over the place into the air.    I can also understand why the gov would not let him manufacture the device for safety reasons.  I like most people am a bit worried about sticking live wires in water.  What if a kid sticks his fingers in there?  what if the electrodes short?  House fire from bad wiring?, etc... etc..  however, with proper engineering, I'm sure a safe design can be contrived to eliminate all these concerns.   

nice work Sprocket,  I'll try to raid the kitchen as well, hopefully my wife won't notice

[Sprocket]

@EMdevices - thanks!  btw, I'm single, so currently it's safe to plunder cutlery - you'd might do well to re-consider...

Speaking of which, I now also need a new Salt & Pepper set! (see pics).  This didn't work out as I hoped.  Despite having visions of emulating Mr. Davey's 'instant-boil' a glass of water antics, and it proving a bitch to build, it seems to perform worse than the first one.  Being a lot smaller, I was boiling a 400mL jar (a large cup approx.) of water in about 60 seconds - so definitely not 'instant'.  The inner bell has a large range of adjustment, but as before, it doesn't seem to effect boil-rate.

I'd like to elaborate a little on what I said about max current near/at boiling - when the first 5A fuse blew, it had been operating until it started to boil.  While this could have been a coincidence, I doubt it.  When using a 13A fuse (which doesn't blow) to boil a bowl of water, if the heater is moved around in the bowl so that no localised hot-spot builds up, everything remains 'quiet' as the water begins to heat.  However, if left in one spot in the bowl, or when all the water is boiling, and big bubbles are being produced, a loud mains-hum ('throbbing' in sync with the bubbles being produced) is heard.  Also, the lights can be seen to dim slightly at times. So though counter-intuitive, there's does seem to be a lot more current flowing at or near the boil-point.  But until I get a clamp meter, I won't know for sure...

[helmut]

@Sprocket

This looks very good.

Good luck with this setup.

helmut

[Sprocket]

Oh boy, I've just made a discovery of sorts - a Davey heater will not boil distilled water!  I knew that distilled water needed an electrolyte for electrolysis, but I assumed that 230V @ 13A would just shrug off these minor inconveniences. Well, having just tried it, I can assure you it doesn't - without electrolyte, nothing happens!  As for my tap-water, well, my "good" results might be down to its 'strange' content as I reported in the electrolysis thread.  btw, the reason I checked with distilled water was because the same brown gunk seemed to be forming on the SS...

So, if a Davey Heater cannot boil all water, can it really be compared with a 'normal' heater?

[DOCV]

I am not sure if anyone has recognized this anomaly yet but I think there is more going on than daveys invention is telling us. If you take a look at the New Zealand Channel 3 report, Peter has two "lamp units" one brassy gold and the other is black. He starts the demonstartion with the brassy gold one. At the base of the unit there is a black spherical shaped object just as the wires join the unit. However on the black "lamp unit" this does not appear at all. The reason I see is that the base of the brassy/gold unit is too shallow to insert this sphere into it so it must remain on the outside. the black unit has a much bigger and deeper base so he can hide it inside.
The big question is what is this spherical shaped unit doing. A perfect case of misdirection. While we are all looking at the bowls and shapes and resonances, there is this little ball unit in the background that no one has noticed.