Surely the answer is yes... but I've just had a plumber adding in and moving
radiators etc. Near the end of the job I asked him casually 'so when does
the inhibitor go in'? meaning of course, 'don't take me for a numpty, I
know you haven't put any in yet, so don't think you can get away without'
and he says 'oh no, you don't need that these days; you had to use it with
the old vented systems but not with these sealed combi jobs. And anyway
there's no header tank to pour it into, to get it in the system'

As so often when I'm faced with an apparently experienced tradesman telling
me that black is actually white, I just caved and left it at that (despite
having personally injected inhibitor into a sealed system before using the
special syringe provided with the stuff, so of course it's 'possible').
This guy has been a qualified plumber all his life (now in his sixties) and
I'd feel very uncomfortable telling him he's talking b*ll*cks. But apart
from the syringe thing, is he? I suppose if no air can get in to the water,
corrosion is less likely isn't it? I'd planned on just injecting some
inhibitor myself later without letting on, for a quiet life, but do I need
to?

David

On Sun, 12 Sep 2004 15:59:46 GMT, "Lobster"
wrote:

Surely the answer is yes... but I've just had a plumber adding in and moving
radiators etc. Near the end of the job I asked him casually 'so when does
the inhibitor go in'? meaning of course, 'don't take me for a numpty, I
know you haven't put any in yet, so don't think you can get away without'
and he says 'oh no, you don't need that these days; you had to use it with
the old vented systems but not with these sealed combi jobs. And anyway
there's no header tank to pour it into, to get it in the system'

As so often when I'm faced with an apparently experienced tradesman telling
me that black is actually white, I just caved and left it at that (despite
having personally injected inhibitor into a sealed system before using the
special syringe provided with the stuff, so of course it's 'possible').
This guy has been a qualified plumber all his life (now in his sixties) and
I'd feel very uncomfortable telling him he's talking b*ll*cks. But apart
from the syringe thing, is he? I suppose if no air can get in to the water,
corrosion is less likely isn't it? I'd planned on just injecting some
inhibitor myself later without letting on, for a quiet life, but do I need
to?

David


Yes you should.

There is a grain of truth in what he says in so far as since the
system is not exposed to the air there is a limit on oxygen content
for corrosion.

However, some corrosion can still happen, and for the few pounds that
a tube of Fernox gel costs, it isn't worth not doing it.
I would avoid the discussion and just do it later.



..andy

To email, substitute .nospam with .gl

In article ,
Andy Hall writes:
Yes you should.

There is a grain of truth in what he says in so far as since the
system is not exposed to the air there is a limit on oxygen content
for corrosion.

That depends how often you have to top it up, i.e. how well he
managed to make it a "sealed system" ;-)

However, some corrosion can still happen, and for the few pounds that
a tube of Fernox gel costs, it isn't worth not doing it.
I would avoid the discussion and just do it later.

ISTR it was a condition of the manufacturer's guarantee for most
boilers when I was trawling though their installation instructions.

--
Andrew Gabriel

"Lobster" wrote in message
...
Surely the answer is yes... but I've just had a plumber adding in and
moving
radiators etc. Near the end of the job I asked him casually 'so when does
the inhibitor go in'? meaning of course, 'don't take me for a numpty, I
know you haven't put any in yet, so don't think you can get away without'
and he says 'oh no, you don't need that these days; you had to use it with
the old vented systems but not with these sealed combi jobs. And anyway
there's no header tank to pour it into, to get it in the system'

As so often when I'm faced with an apparently experienced tradesman
telling
me that black is actually white, I just caved and left it at that (despite
having personally injected inhibitor into a sealed system before using the
special syringe provided with the stuff, so of course it's 'possible').
This guy has been a qualified plumber all his life (now in his sixties)
and
I'd feel very uncomfortable telling him he's talking b*ll*cks. But apart
from the syringe thing, is he? I suppose if no air can get in to the
water,
corrosion is less likely isn't it? I'd planned on just injecting some
inhibitor myself later without letting on, for a quiet life, but do I need
to?

David



Taken from a Potterton installation manual I have to hand - sorry if the
lines are broken, I just copied it from Acrobat (the last line is the
important bit).

"For optimum performance after installation this boiler
and its associated central heating system must be
flushed in accordance with the guidelines given in BS
7593:1992. "Treatment of water in domestic hot water
central heating systems". This must involve the use of a
proprietary cleanser, such as GE Betz Sentinel X300 or
X400, Fernox Superfloc or Salamander System
Cleanser. Full instructions are supplied with the
products, but for immediate information please contact
GE Betz (0044 (0)151 420 9563), Fernox (0044 (0)1799
550 811) or Salamander (0044 (0)121 378 0952)
directly.

For long term protection against corrosion and scale,
after flushing dose the system with an inhibitor such as
GE Betz Sentinel X100, Fernox MB-1 or Copal or
Salamander System Inhibitor in accordance with the
guidelines given in BS 7593:1992.

Failure to flush and add inhibitor to the system will
invalidate the appliance warranty."

Alex

"Alex" wrote in message
...
"Lobster" wrote in message
...
Surely the answer is yes... but I've just had a plumber adding in and
moving
radiators etc. Near the end of the job I asked him casually 'so when
does
the inhibitor go in'? meaning of course, 'don't take me for a numpty, I
know you haven't put any in yet, so don't think you can get away without'
and he says 'oh no, you don't need that these days; you had to use it
with
the old vented systems but not with these sealed combi jobs. And anyway
there's no header tank to pour it into, to get it in the system'

As so often when I'm faced with an apparently experienced tradesman
telling
me that black is actually white, I just caved and left it at that
(despite
having personally injected inhibitor into a sealed system before using
the
special syringe provided with the stuff, so of course it's 'possible').
This guy has been a qualified plumber all his life (now in his sixties)
and
I'd feel very uncomfortable telling him he's talking b*ll*cks. But apart
from the syringe thing, is he? I suppose if no air can get in to the
water,
corrosion is less likely isn't it? I'd planned on just injecting some
inhibitor myself later without letting on, for a quiet life, but do I
need
to?

David



Taken from a Potterton installation manual I have to hand - sorry if the
lines are broken, I just copied it from Acrobat (the last line is the
important bit).

"For optimum performance after installation this boiler
and its associated central heating system must be
flushed in accordance with the guidelines given in BS
7593:1992. "Treatment of water in domestic hot water
central heating systems". This must involve the use of a
proprietary cleanser, such as GE Betz Sentinel X300 or
X400, Fernox Superfloc or Salamander System
Cleanser. Full instructions are supplied with the
products, but for immediate information please contact
GE Betz (0044 (0)151 420 9563), Fernox (0044 (0)1799
550 811) or Salamander (0044 (0)121 378 0952)
directly.

For long term protection against corrosion and scale,
after flushing dose the system with an inhibitor such as
GE Betz Sentinel X100, Fernox MB-1 or Copal or
Salamander System Inhibitor in accordance with the
guidelines given in BS 7593:1992.

Failure to flush and add inhibitor to the system will
invalidate the appliance warranty."

Alex


Oops, forgot to add that's for a sealed combi.

Alex

On Sun, 12 Sep 2004 17:01:37 GMT, "Alex"
wrote:




Oops, forgot to add that's for a sealed combi.

Alex

It doesn't really matter whether it's combi or not, though Alex, it
should still have inhibitor.


..andy

To email, substitute .nospam with .gl

"Lobster" wrote
| This guy has been a qualified plumber all his life (now in his
| sixties) and I'd feel very uncomfortable telling him he's
| talking b*ll*cks.

Good though he may have been in his day, if he hasn't been keeping up to
date on installation techniques he may be missing out other things. Is he,
for example, dealing with the condensate drain properly (if appliccable) or
the pressure relief valve discharge (it's not acceptable to poke it out of a
wall where it might spray boiling water over someone)? What about updating
controls to Part L?

Owain

"Lobster" wrote in message
...
Surely the answer is yes... but I've just had a plumber adding in and
moving
radiators etc. Near the end of the job I asked him casually 'so when does
the inhibitor go in'? meaning of course, 'don't take me for a numpty, I
know you haven't put any in yet, so don't think you can get away without'
and he says 'oh no, you don't need that these days; you had to use it with
the old vented systems but not with these sealed combi jobs. And anyway
there's no header tank to pour it into, to get it in the system'

As so often when I'm faced with an apparently experienced tradesman
telling
me that black is actually white, I just caved and left it at that (despite
having personally injected inhibitor into a sealed system before using the
special syringe provided with the stuff, so of course it's 'possible').
This guy has been a qualified plumber all his life (now in his sixties)
and
I'd feel very uncomfortable telling him he's talking b*ll*cks. But apart
from the syringe thing, is he? I suppose if no air can get in to the
water,
corrosion is less likely isn't it? I'd planned on just injecting some
inhibitor myself later without letting on, for a quiet life, but do I need
to?

David



I put my sealed system in a couple of years ago and originially put
inhibitor in. I've replaced a couple of raditors since as the original
install was 'quick and dirty' and I've decided to re-locate a few
raditiators since. I never topped up the inhibitor and the last radiator I
pulled out had a tiny amount of black water (I wouldn't call it sludge as it
wasn't at all thick) in the bottom.

I'll be adding the inhibitor back in when I get round to it.

(Andrew Gabriel) wrote in
:

In article ,
Andy Hall writes:
Yes you should.

There is a grain of truth in what he says in so far as since the
system is not exposed to the air there is a limit on oxygen
content for corrosion.

That depends how often you have to top it up, i.e. how well he
managed to make it a "sealed system" ;-)

However, some corrosion can still happen, and for the few pounds
that a tube of Fernox gel costs, it isn't worth not doing it.
I would avoid the discussion and just do it later.

My so called sealed system has never been very sealed, I must admit,
but I can certainly say that after 5 years with no inhibitor in it,
the water was brown/black and there was a lot of magnetite in the
pump and the radiators (and presumably everywhere else too). I
think it's worth it.

" but do I need to?"

Yes.

The wizened one was talking about corrosion by dissolved oxygen. The
water in a sealed system system will typically absorb less oxygen than
that in an an open system, but it is likely that there will still be
some oxygen getting into the water. An inhibitor would contain an
oxygen scavenger, which reacts with the oxygen and renders it harmless
before it reacts with the inside surface of the radiators.

ALSO, because the system contains different metals (steel rads, copper
pipes, brass fittings, etc.) and an electrolyte, there will be
galvanic corrosion of the steel radiators. The inhibitor will contain
a pH adjuster which will make the water alkaline and so much less
conductive as an electrolyte, stopping the galvanic corrosion. If the
system hasn't been thoroughly flushed, it may contain acidic flux
residues which will accelerate the galvanic corrosion. The inhibitor
would neutralise any flux residues, within reason.

"Aidan" wrote in message
om...
" but do I need to?"

Yes.

The wizened one was talking about corrosion by dissolved oxygen. The
water in a sealed system system will typically absorb less oxygen than
that in an an open system, but it is likely that there will still be
some oxygen getting into the water. An inhibitor would contain an
oxygen scavenger, which reacts with the oxygen and renders it harmless
before it reacts with the inside surface of the radiators.

ALSO, because the system contains different metals (steel rads, copper
pipes, brass fittings, etc.) and an electrolyte, there will be
galvanic corrosion of the steel radiators. The inhibitor will contain
a pH adjuster which will make the water alkaline and so much less
conductive as an electrolyte, stopping the galvanic corrosion. If the
system hasn't been thoroughly flushed, it may contain acidic flux
residues which will accelerate the galvanic corrosion. The inhibitor
would neutralise any flux residues, within reason.

What is the best inhibitor to use in this sort of system anyway? I was
going to get some more Fernox MB1 but it's a bit pricey (£19/4l).

What is the best inhibitor to use in this sort of system anyway? I was
going to get some more Fernox MB1 but it's a bit pricey (£19/4l).

No idea, I don't know what's in any of them. I use Fernox or Sentinel.
Corrosion is cheaper, in the short term..

"Aidan" wrote in message
om...
What is the best inhibitor to use in this sort of system anyway? I was
going to get some more Fernox MB1 but it's a bit pricey (£19/4l).

No idea, I don't know what's in any of them. I use Fernox or Sentinel.
Corrosion is cheaper, in the short term..

Sentinel X-100 is far cheaper and just as good.

"IMM" wrote in message ...
"Aidan" wrote in message
om...
What is the best inhibitor to use in this sort of system anyway? I was
going to get some more Fernox MB1 but it's a bit pricey (£19/4l).

No idea, I don't know what's in any of them. I use Fernox or Sentinel.
Corrosion is cheaper, in the short term..

Sentinel X-100 is far cheaper and just as good.

Some of the old combined pressure hot water & heating (i.e. the hot
water tank acts as a pressure vessel for the heating) types you're not
allowed to put inhibitor in because of possible contamination of the
potable water.

My old sealed system used to be like this & when it eventually stopped
working I found that a lot of the pipework was almost completely
silted up. It didn't help that the original install had the pump
pumping down so that air got trapped in. I now have a replumbed
sealed system with inhibitor & everything is fine.

PS to the above.

"there will be galvanic corrosion of the steel radiators".

I should have said that the corroison by dissolved oxygen should be
greatly reduced in a sealed system, but that the galvanic/bi-mettallic
corrosion will be unaffected by whether it is an open or a sealed
system. So you need inhibitor.

(adder) wrote in message . com...
"IMM" wrote in message ...
"Aidan" wrote in message
om...
What is the best inhibitor to use in this sort of system anyway? I was
going to get some more Fernox MB1 but it's a bit pricey (£19/4l).

No idea, I don't know what's in any of them. I use Fernox or Sentinel.
Corrosion is cheaper, in the short term..

Sentinel X-100 is far cheaper and just as good.

Some of the old combined pressure hot water & heating (i.e. the hot
water tank acts as a pressure vessel for the heating) types you're not
allowed to put inhibitor in because of possible contamination of the
potable water.


OP back again...

I'm now a bit confused as to which inhibitor I can use in my combi
system. I was going to buy one of those injector kits, but found a
Fernox one in B&Q for £26 so thought it was worth looking into
further, particularly when you can buy a 1L bottle of el cheapo Protex
stuff from Screwfix for only £3.59. What's the difference?

I gather Fernox and Sentinel are the brands to go for, for whatever
reason, and note that on Screwfix's site (http://tinyurl.com/3l4ow),
Sentinel X400 is stipulated as being for indirect systems (combis are
direct, right? ie no h/c water storage, all water at mains pressure?)
whereas the Protex one isn't. Does this relate to potable water
issues as mentioned above? Have I *got* to buy the cheapo stuff, or
go to B&Q for a whopping £26 kit?

Thanks
David

On 15 Sep 2004 15:15:34 -0700,
(Lobster) wrote:

(adder) wrote in message . com...
"IMM" wrote in message ...
"Aidan" wrote in message
om...
What is the best inhibitor to use in this sort of system anyway? I was
going to get some more Fernox MB1 but it's a bit pricey (£19/4l).

No idea, I don't know what's in any of them. I use Fernox or Sentinel.
Corrosion is cheaper, in the short term..

Sentinel X-100 is far cheaper and just as good.

Some of the old combined pressure hot water & heating (i.e. the hot
water tank acts as a pressure vessel for the heating) types you're not
allowed to put inhibitor in because of possible contamination of the
potable water.


OP back again...

I'm now a bit confused as to which inhibitor I can use in my combi
system. I was going to buy one of those injector kits, but found a
Fernox one in B&Q for £26 so thought it was worth looking into
further, particularly when you can buy a 1L bottle of el cheapo Protex
stuff from Screwfix for only £3.59. What's the difference?

I gather Fernox and Sentinel are the brands to go for, for whatever
reason, and note that on Screwfix's site (http://tinyurl.com/3l4ow),
Sentinel X400 is stipulated as being for indirect systems (combis are
direct, right? ie no h/c water storage, all water at mains pressure?)
whereas the Protex one isn't. Does this relate to potable water
issues as mentioned above? Have I *got* to buy the cheapo stuff, or
go to B&Q for a whopping £26 kit?

I've used Fernox products - originally MB-1 but more recently
Superconcentrate gel and Alphi-11 in various systems for over 25
years. I have never had sludging problems at all.

Ergo, I know that these products work.

I am certainly not going to fret over trying to save £20 every few
years when the risk factor in products that are unknowns and may or
may not be good in the long term is many thousands of pounds.

When a chemical is specified as being for indirect systems it refers
to those with a cylinder where the indirect aspect is because the
heating of it is via a coil. Therefore the primary and secondary
water never come into contact.

A combi is a different arrangement where a separate heat exchanger
inside the boiler warms the DHW directly. Again the two sets of water
are kept apart.

Sentinel have a good reputation as well. I would not attempt to
save a few pounds by buying an unknown brand with unknown means to
test its effectiveness. The saving is far outweghed by what is at
stake.


..andy

To email, substitute .nospam with .gl

"Lobster" wrote in message
om...
(adder) wrote in message
. com...
"IMM" wrote in message
...
"Aidan" wrote in message
om...
What is the best inhibitor to use in this sort of system anyway?
I was
going to get some more Fernox MB1 but it's a bit pricey (£19/4l).

No idea, I don't know what's in any of them. I use Fernox or
Sentinel.
Corrosion is cheaper, in the short term..

Sentinel X-100 is far cheaper and just as good.

Some of the old combined pressure hot water & heating (i.e. the hot
water tank acts as a pressure vessel for the heating) types you're not
allowed to put inhibitor in because of possible contamination of the
potable water.


OP back again...

I'm now a bit confused as to which inhibitor I can use in my combi
system. I was going to buy one of those injector kits, but found a
Fernox one in B&Q for £26 so thought it was worth looking into
further, particularly when you can buy a 1L bottle of el cheapo Protex
stuff from Screwfix for only £3.59. What's the difference?

I gather Fernox and Sentinel are the brands to go for, for whatever
reason, and note that on Screwfix's site (http://tinyurl.com/3l4ow),
Sentinel X400 is stipulated as being for indirect systems (combis are
direct, right?

No.

ie no h/c water storage, all water at mains pressure?)
whereas the Protex one isn't. Does this relate to potable water
issues as mentioned above? Have I *got* to buy the cheapo stuff, or
go to B&Q for a whopping £26 kit?

Protex will do. Put two in as it is so cheap.