On 10/09/2012 00:38, Graham. wrote:
On Sun, 09 Sep 2012 20:04:19 +0100, (Alan J. Wylie)
wrote:

Graham. writes:

The last 3 or 4 times I have visited them I have heard a thud, and the
lights blink at the same moment. This happens maybe twice per hour,
but not regularly enough to be able to predict the next event.

...

The bangs however seem to emanate under the floor at the back of the
house near to, or maybe even beyond the party wall. The elderly lady
next door says she hasn't noticed anything.

I thought water would be involved, and we have had torrential rain
recently, however not a drop has fallen this week and I witnessed 3 of
these events last night.

...

I had exactly this problem 20 years ago soon after I moved in to a house
I had just bought. The bangs seemed to be days/weeks apart, though

Eventually diagnosed to a blocked underground watercourse running
through the front garden, water coming in under the floorboards, and
some plonker having left a dangling unterminated live mains cable
lying on the rubble under the floor. The end of the cable was clearly
split and blown apart. I still haven't worked out the exact mechanism:
mains is A/C so electrolysis producing hydrogen shouldn't be the answer.

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.

On Mon, 10 Sep 2012 03:01:10 +0100, Fredxx wrote:

On 10/09/2012 00:38, Graham. wrote:
On Sun, 09 Sep 2012 20:04:19 +0100, (Alan J. Wylie)
wrote:

Graham. writes:

The last 3 or 4 times I have visited them I have heard a thud, and the
lights blink at the same moment. This happens maybe twice per hour,
but not regularly enough to be able to predict the next event.

...

The bangs however seem to emanate under the floor at the back of the
house near to, or maybe even beyond the party wall. The elderly lady
next door says she hasn't noticed anything.

I thought water would be involved, and we have had torrential rain
recently, however not a drop has fallen this week and I witnessed 3 of
these events last night.

...

I had exactly this problem 20 years ago soon after I moved in to a house
I had just bought. The bangs seemed to be days/weeks apart, though

Eventually diagnosed to a blocked underground watercourse running
through the front garden, water coming in under the floorboards, and
some plonker having left a dangling unterminated live mains cable
lying on the rubble under the floor. The end of the cable was clearly
split and blown apart. I still haven't worked out the exact mechanism:
mains is A/C so electrolysis producing hydrogen shouldn't be the answer.

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.

--
Graham.
%Profound_observation%

Graham. wrote:
On Mon, 10 Sep 2012 03:01:10 +0100, Fredxx wrote:

On 10/09/2012 00:38, Graham. wrote:
On Sun, 09 Sep 2012 20:04:19 +0100, (Alan J. Wylie)
wrote:

Graham. writes:

The last 3 or 4 times I have visited them I have heard a thud, and the
lights blink at the same moment. This happens maybe twice per hour,
but not regularly enough to be able to predict the next event.
...

The bangs however seem to emanate under the floor at the back of the
house near to, or maybe even beyond the party wall. The elderly lady
next door says she hasn't noticed anything.
I thought water would be involved, and we have had torrential rain
recently, however not a drop has fallen this week and I witnessed 3 of
these events last night.
...

I had exactly this problem 20 years ago soon after I moved in to a house
I had just bought. The bangs seemed to be days/weeks apart, though

Eventually diagnosed to a blocked underground watercourse running
through the front garden, water coming in under the floorboards, and
some plonker having left a dangling unterminated live mains cable
lying on the rubble under the floor. The end of the cable was clearly
split and blown apart. I still haven't worked out the exact mechanism:
mains is A/C so electrolysis producing hydrogen shouldn't be the answer.
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.

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.


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.



--
Ineptocracy

(in-ep-toc-ra-cy) €“ a system of government where the least capable to
lead are elected by the least capable of producing, and where the
members of society least likely to sustain themselves or succeed, are
rewarded with goods and services paid for by the confiscated wealth of a
diminishing number of producers.

In article ,
The Natural Philosopher writes:
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.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

Andrew Gabriel wrote:
In article ,
The Natural Philosopher writes:
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,


--
Ineptocracy

(in-ep-toc-ra-cy) €“ a system of government where the least capable to
lead are elected by the least capable of producing, and where the
members of society least likely to sustain themselves or succeed, are
rewarded with goods and services paid for by the confiscated wealth of a
diminishing number of producers.

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?

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.

Paul DS.

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...

On 10/09/2012 09:56, The Natural Philosopher wrote:
Andrew Gabriel wrote:
In article ,
The Natural Philosopher writes:
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,


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:
http://www.tlc-direct.co.uk/Book/7.11.2.htm

Fredxx wrote:
On 10/09/2012 09:56, The Natural Philosopher wrote:
Andrew Gabriel wrote:
In article ,
The Natural Philosopher writes:
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,


I have and I get examples of electrode boilers and water heaters, with
no mention to beware of explosive gases.

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



A website closer to home:
http://www.tlc-direct.co.uk/Book/7.11.2.htm


--
Ineptocracy

(in-ep-toc-ra-cy) €“ a system of government where the least capable to
lead are elected by the least capable of producing, and where the
members of society least likely to sustain themselves or succeed, are
rewarded with goods and services paid for by the confiscated wealth of a
diminishing number of producers.

In article ,
writes:
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...

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...

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On 10/09/2012 15:34, The Natural Philosopher wrote:
Fredxx wrote:
On 10/09/2012 09:56, The Natural Philosopher wrote:
Andrew Gabriel wrote:
In article ,
The Natural Philosopher writes:
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,


I have and I get examples of electrode boilers and water heaters, with
no mention to beware of explosive gases.

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



A website closer to home:
http://www.tlc-direct.co.uk/Book/7.11.2.htm



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.

On 10/09/2012 15:05, wrote:
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...


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!

On Monday, September 10, 2012 4:36:09 PM UTC+1, Fredxx wrote:

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...