Heat Exchanger De-scaler

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alan

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One of my jobs this winter was to de-scale my heat exchanger on my Yanmar 3YM30; the engine has done around 850 hours from new, and I am ashamed to say I have never de-scaled it before (it was working fine with temp stable at around 70 degs C over all engine ranges, but I felt I should have a look inside the heat exchanger). So, I read up on this forum and watched various Youtube videos on the subject and finally decided to remove the inner core rather than just back-flush through with de-scaler.

Now to the point of my thread: I tried everywhere I could think of (local shops and on-line) to find one of the commonly used de-scalers mentioned on Youtube (American, English) without any success. I eventually tried my local plumbers supply merchants and they had a few products for flushing radiators etc, and one de-scaler actually meant for heat exchangers!! This product is called DISINEX and is made by FACOT chemicals who are based at:
Facot Chemicals S.r.l.
26010 CAPRALBA (CR) – Italy – Via Crema,44
Tel. +39 0373 45.06.42 – 45.06.43 – Fax +39 0373 45.07.51
www.facotitalia.com

The UK agents for Facot are:
Anglo Nordic Burner Products LTD
12-14 Island Farm Avenue, West Molesey, KT8 2UZ, UK
Paul Barber | Senior Technical Sales
+44 (0) 208 979 0988
paulbarber@anglonordic.co.uk
www.anglonordic.co.uk

If anybody in the UK is interested then the agents may be able to point you to a local retailer (I have not asked them). The most interesting point is that this product is actually meant for heat exchangers and similar, and costs the grand sum of 5 euros per litre!! One litre mixed at 20% was enough for my heat exchanger and bits. Significantly less than so-called marine products.

The second item I needed was four rubber seals which Yanmar sell for around 10 euros each!!! , I found the same item (Vitol) at my local pump/mechanical parts supplier for 40 euro cents each and some new bolts for the end caps at around the same price (total for the O-ring seals and bolts was euro 3.80).
A good place for seals (and bearings) in the UK is Simply Bearings www.simplybearings.co.uk, who have good prices, quick delivery and are very helpful. They also have 65.6 X 3.53 Vitol O-rings which are used on the Yanmar 3YM30 heat exchanger.

The job is quite easy and most time is taken up with removing the alternator and the exhaust elbow in order to get at the heat exchanger end caps easily. I left my bits (actually the heat exchanger bits) in the de-scaler for a couple of hours, along with the 'rubber' tube which runs from the output of the raw water pump to the input of the heat exchanger - this tube was probably the most scaled item in the circuit (but nowhere near blocked).

So, job done for about 10 euros and should be good for another 800 hours!!

Alan.
 
Disinex looks like a useful product to remove severe scaling.

It appears to be hydrochloric acid plus some sulfuric acid. Certain brick and masonry cleaners are common sources of hydrochloric acid in the UK and are readily available from DIY stores and builders merchants

For light scaling I would prefer a sulfamic acid based descaler such as Fernox DS3 which is available in the UK from plumbers merchants. Sulfamic acid is a stronger acid than the weak organic acids but less strong than the strong mineral acids such as hydrochloric acid and sulfuric acid.

Rydlyme is a product sold in the UK for just this purpose but is relatively expensive. It is hydrochloric acid based but its exact composition is a mystery to me.
 
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ip485 said:
Rydlyme - easy to get, reasonably enviromentally friendly and does the job really well.
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It seems like an expensive way to buy dilute hydrochloric acid ...

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JumbleDuck said:
It seems like an expensive way to buy dilute hydrochloric acid ...
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It's not just hydrochloric acid though. The information they publish just does not stack up. 30 years or so ago, when I worked briefly in a analytical chemistry lab I would have had a look at it.
 
VicS said:
It's not just hydrochloric acid though.
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True, but whatever else is in it isn't harmful to health or the environment, which suggests that it probably isn't very harmful to limescale either. It would be interesting to test Rydlyme against HCl of the same pH ...
 
JumbleDuck said:
True, but whatever else is in it isn't harmful to health or the environment, which suggests that it probably isn't very harmful to limescale either. It would be interesting to test Rydlyme against HCl of the same pH ...
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Here https://www.reabic.net/journals/mbi/2016/3/MBI_2016_Bracken_etal.pdf is a comparative trial of mussel degradation by various chemical descalers, including Rydlyme and Rydlyme Marine, with HCl itself as a control. It contains (on p252) this statement:

‘The HCl-control treatment was just as effective as the HCl descalers, suggesting that the presence of descaler constituents additional to HCl do not improve mussel degradation under the experimental conditions. However, greater evidence of a concentration effect in HCl-control treatments could suggest that in descaler treatments, additional constituents (e.g., catalysts) increased the rate of reactivity at lower concentrations, facilitating the maintenance of a similar, rapid reactivity for 25–75% treatments. Such a hypothesis could be investigated in future research.’ [My emphasis.]

I have not undertaken a detailed analysis of the paper, but you and VicS may be interested to take a closer look. The suggestion made by the authors is compatible with the presence of other constituents which aid the acid dissolution process, without being themselves ‘harmful to health or the environment’. Your suggested ‘equivalence’ between environmental harm and ‘harm to limescale’ (i.e. role in dissolution effectiveness) is not necessarily valid.
 
Just soaked my stack in lavatory limescale remover, which seemed to work (and it's nice to know they are now 99% bacteria free). Not that they were bad after 500 hours.
 
JumbleDuck said:
True, but whatever else is in it isn't harmful to health or the environment, which suggests that it probably isn't very harmful to limescale either. It would be interesting to test Rydlyme against HCl of the same pH ...
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Thats the thing that bugs me in their published data. The quoted pH ( although they do say "unreliable" ) does not match the stated concentration of HCl

You can calculate a figure for the HCL concentration from the claimed weight of limescale it will remove. IIRC that checks out OK. You can also calculate what the pH would be if it was just hydrochloric acid . They say generally less than 3. You can calculate the concentration of HCl that would give various pH values. At pH 3, or even pH 2, it will be so dilute it wont do anything very useful in the way of descaling.

If the pH is truy difficult to measure then there must be something in there making it difficult. It's not normally a problem with a glass electrode especially on the acid side of things.

As I said 30 years ago Id have looked at it in the lab.
 
VicS said:
Thats the thing that bugs me in their published data. The quoted pH ( although they do say "unreliable" ) does not match the stated concentration of HCl

You can calculate a figure for the HCL concentration from the claimed weight of limescale it will remove. IIRC that checks out OK. You can also calculate what the pH would be if it was just hydrochloric acid . They say generally less than 3. You can calculate the concentration of HCl that would give various pH values. At pH 3, or even pH 2, it will be so dilute it wont do anything very useful in the way of descaling.

If the pH is truy difficult to measure then there must be something in there making it difficult. It's not normally a problem with a glass electrode especially on the acid side of things.

As I said 30 years ago Id have looked at it in the lab.
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A quick "back of envelope check" this morning reveals this is not so. The claimed removal of scale is greater than that achievable by HCL in the stated concentration range alone.
 
VicS said:
A quick "back of envelope check" this morning reveals this is not so. The claimed removal of scale is greater than that achievable by HCL in the stated concentration range alone.
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You may be confusing "removal" with "complete conversion by acid" ... it may well be that at least some scale is non-reactive product, and that at least some scal detaches without reacting.

All this is by-the-by, as brick cleaner is easierr to get and 1/5th of the price and may well have the same additives, it certainly has the same HCL content, and works just fine. Even if it was a little less efficient (which I doubt) it would still work out cheaper.
 
Hydrozoan said:
Your suggested ‘equivalence’ between environmental harm and ‘harm to limescale’ (i.e. role in dissolution effectiveness) is not necessarily valid.
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Of course. The world is full of basic chemicals marketed at high prices with added woo, so I am naturally suspicious of all proprietary versions of simple things.
 
JumbleDuck said:
Of course. The world is full of basic chemicals marketed at high prices with added woo, so I am naturally suspicious of all proprietary versions of simple things.
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I should perhaps say I have no commercial interest in any descalers, but simply thought the paper relevant to the discussion. You sought a comparison with HCl, and it did that - and did report that under the principal conditions of test it was as effective as the proprietary products. But it also gave some evidence, from dilution results, in support of VicS’s point and I thought that worth noting - and the point that a parallel between harmfulness and effectiveness might not hold.

As a chemist I am prepared to believe that ‘clever chemistry’ can improve the performance of basic materials - but like you I always look, as carefully as information allows, to try to see what I’m getting for my money.
 
Hydrozoan said:
I should perhaps say I have no commercial interest in any descalers, but simply thought the paper relevant to the discussion. You sought a comparison with HCl, and it did that - and did report that under the principal conditions of test it was as effective as the proprietary products. But it also gave some evidence, from dilution results, in support of VicS’s point and I thought that worth noting - and the point that a parallel between harmfulness and effectiveness might not hold.
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Oh yes, and jolly interesting too. I'm sorry if I sounded ungrateful - I was trying to explain where my a priori scepticism comes from, not shoot you down.
 
JumbleDuck said:
Oh yes, and jolly interesting too. I'm sorry if I sounded ungrateful - I was trying to explain where my a priori scepticism comes from, not shoot you down.
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Not at all - and my post did not emphasise the 'acid equivalence' in the principal part of the experiment, as the focus of discussion seemed to be on the possible differences.

(In passing, I have a different engine and a bronze (?) H/E tubestack, and just lightly abrade any deposits to 'loosen' the stack in the housing and poke out the (rare) bits of anything that can be found in a tube. I have never acid cleaned it, believing that it will destroy a thin 'passivation layer' of copper corrosion product and increase engine anode consumption - but I am lucky in finding little scale.)
 
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