Hydrogen in Central heating System
Ken Hargreaves
I've looked in the FAQ but can't see this covered...
Following the fitting of a new condensing boiler (see previous post) to an
18 year old open vented CH/HW system, I've had persistent problems with
hydrogen being generated in the system at higher flow temperatures (> 65
deg C). There were no problems with this before the new boiler was fitted.
The system volume is 280 litres and it has 3 litres of Sentinel X100 in it.
It's pretty conventional with steel radiators and 15 mm copper piping.
Having changed one radiator I know there's quite a bit of black sludge
(ferric (?) oxide) in the radiator bottoms and, as far as I understand,
this is the reaction product from the water/metal reaction that also
produces the hydrogen.
I know that the system wasn't chemically flushed when the boiler was
installed, just a single water change (cowboy installers!). So, my
question is: is it worth putting X400 or similar through to clean it out,
or is the hydrogen generation a symptom of serious corrosion which is
beyond the abilities of an inhibitor to deal with? The pipework is in
fairly good condition and there are no leaks.
Ken.
John Laird
In article <34BF21...@nortel.co.uk>, Alan Briggs <Alan.Brig...@nortel.co.uk> writes:
> Clive Elsmore wrote:
>
> ...........
>> I have heard from a reliable source:-) of a plumber who fitted 3
>> pressurised Potterton condensing boilers in new systems but with Fernox
>> instead of Sentinel X100 or Copal(?) for the aluminium heat exchangers.
>> Hydrogen resulted big time, the heat exchangers got eaten away and they all
>> eventually started leaking badly and had to be replaced! If Fernox or
>> similar could still be in the system and the exchanger is Al I would flush
>> it out thoroughly asap and put in fresh Sentinel X100.
>> Clive
>
> I'm thinking of replacing my (very) old boiler with a new condensing
> model so your comments are of great interest. Are you saying that
> Fernox will attack aluminium or simply that it does not protect
> aluminium from corrosion?
>
Probably the latter. The bottle of Fernox sez "not suitable for use with
boilers fitted with aluminium heat exchangers". Having painstakingy poured
4 litres of this via a funnel into a narrow vent pipe, I spent even longer
reading every single word of the boiler manuals looking for some clue as
to whether the exchanger is cast iron, stainless steel, ally, egg-boxes.
Zip. Sort of annoyed the plumbers merchants didn't query first...
--
John Laird (jo...@yrl.co.uk) "I have discovered a truly elegant sig,
Yezerski Roper Ltd sadly there is no room here to show it."
http://www.yrl.co.uk
Alan Briggs
Clive Elsmore wrote:
...........
> I have heard from a reliable source:-) of a plumber who fitted 3
> pressurised Potterton condensing boilers in new systems but with Fernox
> instead of Sentinel X100 or Copal(?) for the aluminium heat exchangers.
> Hydrogen resulted big time, the heat exchangers got eaten away and they all
> eventually started leaking badly and had to be replaced! If Fernox or
> similar could still be in the system and the exchanger is Al I would flush
> it out thoroughly asap and put in fresh Sentinel X100.
> Clive
I'm thinking of replacing my (very) old boiler with a new condensing
model so your comments are of great interest. Are you saying that
Fernox will attack aluminium or simply that it does not protect
aluminium from corrosion?
--
- Alan Briggs -
Ken Hargreaves
Clive Elsmore <clive....@jet.uk> wrote in article
<01bd21d7$e0d23640$0571...@9600219-cge.jet.uk>...
>
>
> Ken Hargreaves <kenh*@ite.ac.uk> wrote in article
> <01bd21ba$2398ebe0$7488...@bup016.nbu.ac.uk>...
> > Following the fitting of a new condensing boiler (see previous post)
to
> an
> > 18 year old open vented CH/HW system, I've had persistent problems with
> > hydrogen being generated in the system at higher flow temperatures (>
65
> > deg C).
>
>! If Fernox or
> similar could still be in the system and the exchanger is Al I would
flush
> it out thoroughly asap and put in fresh Sentinel X100.
> Clive
>
I don't think there could have been any old inhibitor left in the system as
it was completely drained, refilled with water, drained, refilled then X100
added (first post didn't make this clear). If I do decide to chemically
flush it then I may well put in Fernox Copal as there is a large sticker on
the boiler saying that this is the only one you should use. Mind you, the
installation guide says that X100 is OK as well!
Ken
David Frith
>
an
> 18 year old open vented CH/HW system, I've had persistent problems with
> hydrogen being generated in the system at higher flow temperatures (> 65
fitted.
> The system volume is 280 litres and it has 3 litres of Sentinel X100 in
it.
Funnily enough I'm experiencing the same problem having changed the boiler
to a condensing type. I flushed the system several times whilst working on
different aspects of it and only had problems after I put the inhibitor in.
I've used Fernox Copal as recommended by the manufacturers of the boiler.
Having read the other threads I'm now worried that my aluminium heat
exchanger is being converted to hydrogen (how aluminium produces hydrogen I
don't know but then I didn't finish my A level chemistry course). Note that
I didn't have the problem UNTIL I put the inhibitor in. Any wise words as
to whether I have a real problem?
--
David Frith Fujifilm Electronic Imaging Next time the devil reminds
Principal Engineer Hemel Hempstead, Herts you of your past, remind him
david...@ffei.co.uk +44 1442 343083 of his future.(See Rev 20:10)
Mike Paley
My parents' system is just neat water and has been no problem for 22 years.
Mine's just water as well, and the installation guide doesn't mention
inhibitor.
Is it all that "necessary" ?
--
Comm again, Mike.
My friend used to go to parties on the moon. He stopped going, so I asked
him why and he replied. "They've got no atmosphere."
Ex Windows 95 user Ex Turnpike user.
More info.: http://www.paley.demon.co.uk/ [1998:01:10]
Andrew Gabriel
In article <520046...@paley.demon.co.yuk>,
Mike Paley <mi...@paley.demon.co.yuk> writes:
>My parents' system is just neat water and has been no problem for 22 years.
>Mine's just water as well, and the installation guide doesn't mention
>inhibitor.
It can be disasterous putting inhibitor into an old system which
has never had it before.
--
Andrew Gabriel
Consultant Software Engineer
Mike Paley
In article: <69q5jl$1...@cucumber.demon.co.uk> and...@cucumber.demon.co.uk
(Andrew Gabriel) writes:
:) In article <520046...@paley.demon.co.yuk>,
:) Mike Paley <mi...@paley.demon.co.yuk> writes:
:) >My parents' system is just neat water and has been no problem for 22
years.
:) >Mine's just water as well, and the installation guide doesn't mention
:) >inhibitor.
:)
:) It can be disasterous putting inhibitor into an old system which
:) has never had it before.
:)
Interesting, although I wasn't thinking of doing it to either system, but
thanks for the warning.
Chris J Dixon
Andrew Gabriel wrote:
>In article <520046...@paley.demon.co.yuk>,
> Mike Paley <mi...@paley.demon.co.yuk> writes:
>>My parents' system is just neat water and has been no problem for 22 years.
>>Mine's just water as well, and the installation guide doesn't mention
>>inhibitor.
>
>It can be disasterous putting inhibitor into an old system which
>has never had it before.
All this talk about adding an inhibitor was beginning to make me
think I should do something about it.
Is the problem that all the tiny seepages which have self-sealed
will open up again?
Chris
--
Chris J Dixon Nottingham UK
chris...@easynet.co.uk
Have dancing shoes, will ceilidh.
Andrew Gabriel
In article <34c104c1...@news.easynet.co.uk>,
chris...@easynet.co.uk (Chris J Dixon) writes:
>Andrew Gabriel wrote:
>
>>It can be disasterous putting inhibitor into an old system which
>>has never had it before.
>Is the problem that all the tiny seepages which have self-sealed
>will open up again?
I believe so. The warning came from a plumber who replaced my
parents' hot water cylinder when I suggested that it might be
worth adding inhibitor to the 40 year old heating system.
Interestingly, without inhibitor, none of the original parts
of the heating system have corroded, but pretty well all of
the later additions show some signs. I can only assume that
the limited lifetime design feature hadn't been developed
40 years ago, but was shortly thereafter to ensure a
continuous replacement of plumbing fittings is required :-(.
Mark Evans
David Frith (david...@ffei.co.uk) wrote:
:
: Funnily enough I'm experiencing the same problem having changed the boiler
: to a condensing type. I flushed the system several times whilst working on
: different aspects of it and only had problems after I put the inhibitor in.
: I've used Fernox Copal as recommended by the manufacturers of the boiler.
: Having read the other threads I'm now worried that my aluminium heat
: exchanger is being converted to hydrogen (how aluminium produces hydrogen I
Reacts with the water to produce Aluminium hydroxide and hydrogen, most likely.
Aluminium is actually a rather reactive metal, but it forms an inert oxide,
which will protect the metal. However anything which strips the oxide will
cause it to react.
Mark Evans
Clive Elsmore (clive....@jet.uk) wrote:
:
: Actually, my impression from the tale was the former - that the standard
: Fernox actively attacks the Aluminium. It must be that, because the
Or attacks Aluminium oxide. If you remove the oxide from Aluminium,
either chemically or by abrasion in an oxygen free atmosphere then
put it in water it will fizz away quite enthusiastically to leave
a hydroxide solution.
In air the metal will acquire an oxide coating in seconds which
will protect it from further oxidation.
This, combined with low melting point and the fact that
aluminium burns quite well in air (See HMS Sheffield)
makes aluminium tricky to weld.