I suppose AC electrolysis of water gives two parts hydrogen and 1 part oxygen from *both* electrodes. I wonder if that is the mechanism? It does sound a bit like percussive gas ignition. Earlier I suggested it might be due to superheated steam.
I think you'll find AC and water just produces heat, and not much in the way of explosive gases.
When I was a kid I used to fill lemonade bottles full of H2 by displacing salt water from the -ve pole of my Hornby transformer.
I think you will find you are wrong. Otherwise you could reverse electrolysis by simply switching polarity every half an hour. Or every ten years. Or 50 times a second...
In fact its even more dangerous as H2 and O2 are formed at both electrodes.
Given that electrode boilers generate no gas, I'd say you are wrong.
I would guess the ion recombination time to for the electrolysis products to form is longer than 100th of a second, so they never do.
Exactly. They never turn back into water again.
Google it. Everybody says the same thing. You get H2 and O2 together and its a bloody explosive mix,
Is the conservatory new? Could the thud be emanating from a drain / manhole cover / similar?
Is the water pipe shared? Water hammer can be a dull thud if pipes run under floors, appear at random?
Got to agree. We have a medical humidifier which works by using carbon electrodes to heat the water. As far as I can see, this really is just a couple of rods running 240V AC straight into water.
With demin water, nothing happens (not enough conduction). With a small amount of tap water added, we get the required steam. With neat tap water we get copious steam because our tap ware if very hard.
Paul DS.
Looking at the descriptions available it's not totally obvious but I suspec= t that the amount of gas is kept down by using high voltage, low current de= nsity and fairly pure water, so that most of the heat is generated by resis= tive heating between the electrodes. There is obviously some hydrogen gener= ated, though, since apparently this caused an explosion in Switzerland whic= h injured a couple of people. That would have been an electrode boiler on a= rather different scale - in the megawatt range...
I have and I get examples of electrode boilers and water heaters, with no mention to beware of explosive gases.
A website closer to home:
indeed. That because at the currents and conditions they use, its far more likely that steam will outnumber H2 by a million to one or so
that the amount of gas is kept down by using high voltage, low current density and fairly pure water, so that most of the heat is generated by resistive heating between the electrodes. There is obviously some hydrogen generated, though, since apparently this caused an explosion in Switzerland which injured a couple of people. That would have been an electrode boiler on a rather different scale - in the megawatt range...
That seems to have been an electrode jet boiler (where you heat just a jet of water so you get instant steam, without having to first heat a whole tank full to boiling point). That incident seems to have halted their use according to one article I read.
More usual electrode boilers are just electrodes dunked in a tank of water, and they don't generate hydrogen according to everything I can find on google, and my own experience as a teenager...
Excellent, you accept that under AC fault/water conditions, like a potential fault outlined in this thread, that any "explosions" will be a likely to be a result of rapid steam generation rather than from a hydrogen/oxygen explosion.
Whilst most heat is generated resistively, in much the same way fuels cells function, having a thin film of hydrogen or oxygen at each electrode with reverse polarity will convert that film back into hydrogen or oxygen ions respectively. The process is reversible.
Have you got any more details of this explosion. Journalists usually don't have a clue, and will write the most sensational nonsense!
Indeed - in this case though the reason I commented this had 'apparently' happened was that the information came from a competing manufacturer of electrode boilers who were claiming their design was safer...
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