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#218420 04/19/17 01:43 PM
Joined: Mar 2015
Posts: 76
In another thread there was some discussion about Electrode boilers brought about by a vintage advert for an individual tap water heater that works on that principle now I can see how they work with tap water cos its conductive( to a degree) however I remember one in my old job that heated deionised water which doesn't conduct so I want to know how do they work?? Anyone know?

Joined: Mar 2005
Posts: 1,213
Everything is a conductor if the voltage is high enough. laugh

But I'm puzzled as to why an electrode boiler would be used with DI water, as it would not only be terribly inefficient (less ions mean less current and slower heating), but would also contaminate the DI water with ions sputtered from the hot electrodes. Was it an electrode boiler or an electrodeionization machine which doesn't boil the water, but instead uses electrodes separated from the DI stream by special membranes to create an electrical charge field to draw ions through those special membranes?

Joined: Mar 2015
Posts: 76
It was an electrode boiler used to make very hot water for an anodizing plant I wonder if the boiler heated normal water which then transfers its heat to the deionized water what you think? The machine I'm concerned with works on 440volts 3 phase

Joined: Jul 2002
Posts: 8,443
Likes: 3
Sorry to come into this so late, I would like to give you an explanation as to how an electrode boiler works.
Simply, water out of the tap (faucet), has "impurities" in it, that is not to say the water is impure, what I'm talking about is the trace elements that could be in the water, it could be cobalt, magnesium, calcium, you name it, but they are there, but this chemical make-up, affects the electrical resistance of the water in the electrode boiler, this is used to great effect.
As you said above, you had a boiler that tried to heat de-ionised water, that for a start is not going to work that well.
The reason behind that, is because pure water does not conduct electricity and to be fair this sort of water is bad for our health, if it is drank on a regular basis.

But, the electrode boiler has 3 live probes inside the heating chamber, at different heights, normally 50mm between them, there is a temperature probe below the electrodes, this starts and stops the heating via a relay or contactor.
Normally, there is also a "run dry" switch at the bottom of the chamber that turns off the power to the electrodes should the chamber have no water.

Effectively what happens, when the chamber is full, the heating process starts, current flows through all of the probes, the water is boiled pretty much instantly through electrical resistance through the water.

Not long after I finished my time as an Electrician, I got sent to a factory, that used a large electrode boiler that used 400V, to create steam for the presses (it was a clothing factory, when we had them here), I was scared by the size of the thing, the tank was massive and someone had mucked around with the tank pressure switch, I walked back to my van to get my Duspol tester and the tank split down the side, that bought the whole factory to a halt.
Good times.......

Joined: Mar 2015
Posts: 76
Hi you were luck you had to go back to your van that could of been horrible if you'd been in the room at the time. I now understand more of how these boilers work and I'm sure that the one I saw worked by heating normal water and then using that to heat the Di water in the same manner as domestic central heating worked. One thing I remember the whole place was very ineficient using many kilowatts to generate heat with then went out through the holes in the roof! Happy days NOT

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