On Monday, September 10, 2012 1:29:55 PM UTC+1, Paul D Smith wrote:
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.

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.

Looking at the descriptions available it's not totally obvious but I suspect 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...