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Default CH system descaling quandry

I wish to do a thorough descaling and de-sludging of my sealed CH
system, and have bought a large tub of Fernox DS40 to accomplish this (I
hope).

I note on the instructions that it says to allow 7 days for it to work
on all-steel systems, but only 4 *hours* for those containing aluminium
rads.

My problem is that I have a combination of both.

Can anyone suggest a work-flow I can use here to ensure a proper job is
done throughout, please?

Note: My system is split into 2 circuits, with flow control valves
operated by the timer programmers. All the aluminium rads are located on
the downstairs circuit and the older steel one's on the upstairs.
Obviously, I *can* isolate the alu rads by screwing down the valves, but
this would mean I would have no heat to downstairs at all for around a
week, and winter is not over yet. And no, the job can't wait until the
Spring. However, if it's a must, then I will do it. :-(

Nigel
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Default CH system descaling quandry

On Sat, 27 Jan 2007 10:25:39 +0000, Siggy wrote:

I wish to do a thorough descaling and de-sludging of my sealed CH
system, and have bought a large tub of Fernox DS40 to accomplish this (I
hope).

I note on the instructions that it says to allow 7 days for it to work
on all-steel systems, but only 4 *hours* for those containing aluminium
rads.

My problem is that I have a combination of both.

Can anyone suggest a work-flow I can use here to ensure a proper job is
done throughout, please?

Note: My system is split into 2 circuits, with flow control valves
operated by the timer programmers. All the aluminium rads are located on
the downstairs circuit and the older steel one's on the upstairs.
Obviously, I *can* isolate the alu rads by screwing down the valves, but
this would mean I would have no heat to downstairs at all for around a
week, and winter is not over yet. And no, the job can't wait until the
Spring. However, if it's a must, then I will do it. :-(

Nigel


Acid descaling is surprisingly popular especially considering that
limescale is rarely the principal problem with a heating system.

What are the symptoms you are trying to tackle, what is the underlying
problem and how are you going to address those?


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards
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Default CH system descaling quandry

On Sat, 27 Jan 2007 10:25:39 GMT, Siggy
wrote:

I wish to do a thorough descaling and de-sludging of my sealed CH
system, and have bought a large tub of Fernox DS40 to accomplish this (I
hope).

I note on the instructions that it says to allow 7 days for it to work
on all-steel systems, but only 4 *hours* for those containing aluminium
rads.


So take it back and get something designed for aluminium ones that may
also work on steel?

There must be something designed to do this. You can't be the first to
have this problem.
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Default CH system descaling quandry

Ed Sirett wrote:


Acid descaling is surprisingly popular especially considering that
limescale is rarely the principal problem with a heating system.


It isn't really the limescale I want rid of, as much as the black stuff.
I have had a persistent pressure loss for some time now and I'm buggered
if I can find it. Hence I have had to frequently top up the system with
more fresh (oxygenated) water via the filling loop. Being a lazy
*******, I haven't been quite as diligent about refreshing the
anti-corrosion inhibitor, so I keep clogging up my DHW heat exchanger.
I have just swapped it out with my handy spare for the 4th time now, and
it's getting to be a pain in the derriere as this occasion is only 3
months on from the last swap out! I figure that my combi main heat
exchanger also has collected much of the muck, and to cut a loooong
story short, I just want to clean the whole fecking lot out once and for
all and shove some anti-leak chemical in (which I have also obtained)
before another fresh dose of corrosion inhibitor.....

What are the symptoms you are trying to tackle, what is the underlying
problem and how are you going to address those?



See above. Then suicide, if that doesn't work ...
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Default CH system descaling quandry

EricP wrote:


So take it back and get something designed for aluminium ones that may
also work on steel?


If it ain't in Google, then it ain't in The Depot!

There must be something designed to do this. You can't be the first to
have this problem.



I bet I am. Feckin' life story, Eric. Thanks for dropping by, though.


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Default CH system descaling quandry

On Sun, 28 Jan 2007 00:08:02 GMT, Siggy
wrote:


See above. Then suicide, if that doesn't work ...


As the crucifix seems to have stopped working, this may be the only
path left.

You must try to find the leak. With no puddles on the floor, it is
probably going out the pressure relief valve, or even across to the
DHW side and out the tap.

Have you examined the relief valve?

Have you looked at the pressure vessel?

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Default CH system descaling quandry

On 2007-01-28 00:26:13 +0000, EricP said:

On Sun, 28 Jan 2007 00:08:02 GMT, Siggy
wrote:


See above. Then suicide, if that doesn't work ...


As the crucifix seems to have stopped working, this may be the only
path left.

You must try to find the leak. With no puddles on the floor, it is
probably going out the pressure relief valve, or even across to the
DHW side and out the tap.

Have you examined the relief valve?

Have you looked at the pressure vessel?


Another one along these lines is leaking spindles on radiator valves.
A small leak may only be happening when the system is hot and of an
amount that it is evaporated by the heat without showing very much or
at all from the caps. Try going around and removing each cap for a
look. Replace any radiator valves showing signs of leaking with new,
good quality ones such as Pegler. Spindles of motorised valves are
another candidate.

Pressure relief valve is certainly a favourite. If this is leaking,
then a replacement is the solution since they are impossible to repair
reliably.

Concerning a thorough system clean; a better approach, which would not
have issues with different materials and use of chemicals, would be to
remove each radiator in turn, take it outside and flush it with a
pressure washer or hose on the mains. While the radiator is removed,
flush system water out at the radiator position from the valves.
This means that crud is flushed out and not around the system and is
much more effective than circulating an acid cleaner.
Care, because sludgy water is an indellible dye. Small sandwich bags
rubber banded over radiator tails is a good plan while moving them
around.

An alternative that would be better than adding a cleaner and
circulating would be to rent a pressure flushing machine and use that
to power flush the system.


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Default CH system descaling quandry

EricP wrote:
On Sun, 28 Jan 2007 00:08:02 GMT, Siggy
wrote:

See above. Then suicide, if that doesn't work ...


As the crucifix seems to have stopped working, this may be the only
path left.


Do not jest!! )

You must try to find the leak.


Damn, and here was me hopin it would be you! :-p

With no puddles on the floor,


Perhaps it is just a faulty prostate instead?

it is probably going out the pressure relief valve, or even across to the
DHW side and out the tap.


I replaced the DHW Watersection valve in 2001 due to corrosion, which I
accidentally discovered when I couldn't turn the attached adjusting
wheel which alters the dhw flow rate. It had locked up solid due to not
replacing the the combicare cartridge often enough. I have done so
religiously ever since, and the wheel still keeps on turnin! Can't see
any sign of weeping or corrosion although it is all a bit packed with
gubbins in there to get a proper view. I don't feel any moistness when I
run my fingers around the many joints there. :-s

Have you examined the relief valve?


Yes, and there were occasions when we observed small drips coming from
the vent pipe outside the front door. But this was before we replaced
the CH pressure vessel last summer, and I dont' *think* it has happened
again since, although I will try taping a plastic sandwich bag around
the end to catch the drips if any.

I have also done a mains pressure back flush through the boiler and
vented out through the PRV by turning the valve knob to open it fully
and allowing it to 'shunt' back into the closed position. As you will
know, they are sprung loaded and when you pass a certain point of no
return, the valve slams shut again. I realise that it is not advisable
to do this, as grit can get trapped etc in the seal and cause a leak.
But I power flushed it at mains pressure at the same time as operating
the valve, so hopefully it shouldn't have trapped any debris?

Have you looked at the pressure vessel?


Yup, see above. Told you it was a loooong story! :-((


I am now of Andy's view that it must be a weeping rad valve or someat
similar. Hence my current choice for introducing a leak sealer chemical,
just to eliminate that area of possibility.
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Default CH system descaling quandry

Andy Hall wrote:


Another one along these lines is leaking spindles on radiator valves.
A small leak may only be happening when the system is hot and of an
amount that it is evaporated by the heat without showing very much or at
all from the caps. Try going around and removing each cap for a look.
Replace any radiator valves showing signs of leaking with new, good
quality ones such as Pegler. Spindles of motorised valves are another
candidate.


Hi Andy. Yes, this is a conclusion I have come to, hence my current
project to introduce anti-leak chemical into the system. But I want to
de-sludge it all first.

Pressure relief valve is certainly a favourite. If this is leaking,
then a replacement is the solution since they are impossible to repair
reliably.


See my reply to EricP.

Concerning a thorough system clean; a better approach, which would not
have issues with different materials and use of chemicals, would be to
remove each radiator in turn, take it outside and flush it with a
pressure washer or hose on the mains. While the radiator is removed,
flush system water out at the radiator position from the valves.
This means that crud is flushed out and not around the system and is
much more effective than circulating an acid cleaner.
Care, because sludgy water is an indellible dye. Small sandwich bags
rubber banded over radiator tails is a good plan while moving them around.


Gulp. I did all that when I put the new boiler in in 1997. I was a fit
young thing then! Don't want to go through all that again in a hurry,
especially as it's winter still and I was hoping a chemical treatment
would suffice for my purposes. If I was replacing the boiler, then I
would replace all the remaining steel rads and valves too. But I hope
that won't be necessary for at least another 6 - 12 months, as I have
several other major projects on hand at present to occupy me with.

An alternative that would be better than adding a cleaner and
circulating would be to rent a pressure flushing machine and use that to
power flush the system.


'Tis an idea. Hadn't thought of that. But I liked the fact that the DS40
states it *would* return the rads and pipework to bare metal condition. :-s

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Default CH system descaling quandry

Siggy wrote:
EricP wrote:
On Sun, 28 Jan 2007 00:08:02 GMT, Siggy



it is probably going out the pressure relief valve, or even across to the
DHW side and out the tap.


I replaced the DHW Watersection valve in 2001 due to corrosion, which I
accidentally discovered when I couldn't turn the attached adjusting
wheel which alters the dhw flow rate. It had locked up solid due to not
replacing the the combicare cartridge often enough. I have done so
religiously ever since, and the wheel still keeps on turnin! Can't see
any sign of weeping or corrosion although it is all a bit packed with
gubbins in there to get a proper view. I don't feel any moistness when I
run my fingers around the many joints there. :-s


ps. I do realise that it could of course be leaking *internally* as you
imply. However, that would suggest an intermittent pressure loss
situation occurring? When I went away for Xmas for a week it had still
dropped the usual .1 to .15 of a Bar when we got back home and no-one
had been using any taps, and we don't have any dripping ones. :-s


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Default CH system descaling quandry

On Sun, 28 Jan 2007 10:17:46 GMT, Siggy
wrote:

ps. I do realise that it could of course be leaking *internally* as you
imply. However, that would suggest an intermittent pressure loss
situation occurring? When I went away for Xmas for a week it had still
dropped the usual .1 to .15 of a Bar when we got back home and no-one
had been using any taps, and we don't have any dripping ones. :-s


I will retire in total bafflement then. (

As usual you are exceeding all bounds in Awkwardness. )

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Default CH system descaling quandry

EricP wrote:


I will retire in total bafflement then. (


Typical! You have your way with me and I divulge my whole boiler life
story, much agin my better judgement, and then you sod off and leave me
holding the .. errr .. toolbox. Pah!

As usual you are exceeding all bounds in Awkwardness. )


See ya in DiscGen then. ;-)
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Default CH system descaling quandry

On 2007-01-28 09:50:55 +0000, Siggy said:

An alternative that would be better than adding a cleaner and
circulating would be to rent a pressure flushing machine and use that
to power flush the system.


'Tis an idea. Hadn't thought of that. But I liked the fact that the
DS40 states it *would* return the rads and pipework to bare metal
condition. :-s


The concern is how much metal it will remove in the process. The
effectiveness also depends on how much crud there is because the
solution can only dissolve so much. Is it at a level where the
bottoms of the radiators feel cool in the centre?


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Default CH system descaling quandry

On 2007-01-28 09:42:02 +0000, Siggy said:


I am now of Andy's view that it must be a weeping rad valve or someat
similar. Hence my current choice for introducing a leak sealer
chemical, just to eliminate that area of possibility.


I would go round and do a physical check on all the radiator valves.
If there are any leaking, you can try packing the gland and tightening
the nut.

Leak sealer is more geared for leaks around joints and so on. I am
dubious that it would reliably fix a radiator valve leak.



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Default CH system descaling quandry

On Sun, 28 Jan 2007 00:08:02 +0000, Siggy wrote:

Ed Sirett wrote:


Acid descaling is surprisingly popular especially considering that
limescale is rarely the principal problem with a heating system.


It isn't really the limescale I want rid of, as much as the black stuff.
I have had a persistent pressure loss for some time now and I'm buggered
if I can find it. Hence I have had to frequently top up the system with
more fresh (oxygenated) water via the filling loop. Being a lazy
*******, I haven't been quite as diligent about refreshing the
anti-corrosion inhibitor, so I keep clogging up my DHW heat exchanger.
I have just swapped it out with my handy spare for the 4th time now, and
it's getting to be a pain in the derriere as this occasion is only 3
months on from the last swap out! I figure that my combi main heat
exchanger also has collected much of the muck, and to cut a loooong
story short, I just want to clean the whole fecking lot out once and for
all and shove some anti-leak chemical in (which I have also obtained)
before another fresh dose of corrosion inhibitor.....

What are the symptoms you are trying to tackle, what is the underlying
problem and how are you going to address those?



See above. Then suicide, if that doesn't work ...


I think most of the other replies have just about covered everything. You
are sure it's not a failed exp. vessel.

Really a standard desludgant (eg X 400) should be all you need, together
with any or all of the following:

Power flush machine.
Main filling loop flushing.
Removal or radiators and hosing down.

After such wokr you may find that you still get some further blockage of
the 2ndary heatXer, but hopefully for the last time.


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards
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