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Corrosion inhibitor


dor

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A recent post set me thinking...

 

We are told the main reason to change (blue) antifreeze every two years or so is to do more with the corrosion inhibitors than the antifreeze properties. The latter is easy to check by taking a sample and putting it in the freezer, but there is no easy way to check if the corrosion inhibitor is working (assuming it is actually required in a closed system).

 

So rather than change the whole coolant with a new mixture, could we just remove a small amount and replace with central heating inhibitor as sold by the likes of Screwfix? The same goes for the boat central heating system which also needs antifreeze and corrosion inhibitor.

 

There can't be much functional difference between a central heating system with steel radiators and a boat's coolant system. At £7 for enough to do 100 litres it seems a much more economic way to do it.

 

I accept that, like oil, it is a small difference in the overall scheme of things, but some people might be more conscious of the cost.

 

How often do people drain down their CH at home and replace with new inhibitor?

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Morris Oils make this product which I used a couple of winters ago while I worked out how to drain and flush the entire system.I removed 1 litre of the existing coolant (total about 30 litres, so 3%).

 

http://www.morrislubricantsonline.co.uk/ankorsol-anti-corrosion-fluid.html

 

I can't see anything that says how long the protection lasts for, or how you test to see if it is still working. I suppose you could just add another litre every couple of years, while checking that you still have sufficient antifreeze protection....??

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To test the corrosion inhibitors in my central heating, I drain some out, enough to completely fill (so you don't add any more oxygen) a jam jar, add some untreated virgin steel wool, the finer the better, Screwfix sell it for decorators or plumbers, brillo pads do not work lol.

 

Shake every day and observe the colour of the steel wool, and look for any rust deposits.

 

Review in a month, if the steel wool is still shiny, your inhibitors are ok.

 

You can also buy domestic heating inhibitors with anti freeze properties too. To add more confusion lol.

 

Be aware, that car type antifreeze also raises the boiling point of the water to beyond 100 c even if not under pressure, so if you have an engine that is prone to overheating, then an alternative inhibitor needs to be looked at with caution, I doubt manufacturers will issue data on boiling point changes based on pressure and various dilutions.

 

If in doubt, carry enough of the old type antifreeze to go back to a solution you know works.

Just my thoughts.

Richard

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A few steel nails in the jam jar works OK too.

 

Central heating corrosion inhibitors last about 5 years IME based on Fernox MB1 or the Screwfix stuff. You can tell it knackered when the rads start to need bleeding.

 

N

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The way to test is firstly in the freezer as previously suggested. Secondly to check for anti corrosion is to see if the colour is still there. If it were causing corrosion the water would be going brown. If you ever had seen water from a non treated cooling system you would know what I mean.

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Morris Oils make this product which I used a couple of winters ago while I worked out how to drain and flush the entire system.I removed 1 litre of the existing coolant (total about 30 litres, so 3%).

 

http://www.morrislubricantsonline.co.uk/ankorsol-anti-corrosion-fluid.html

 

I can't see anything that says how long the protection lasts for, or how you test to see if it is still working. I suppose you could just add another litre every couple of years, while checking that you still have sufficient antifreeze protection....??

You might find that Morris Oils have dropped this line. Last time I looked I couldn't find it on their site and the above link wouldn't work for me.

 

 

Frank

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Recently after 9 years in service I thought it about time I did something with the antifreeze in my engine and central heating. I decided to replace the lot with like for like blue glycol. I drained 30 Ltrs from the engine cooling system and 12 Ltrs central heating. Having mixed the new antifreeze to refill the systems I compared it with the old I had removed and could not tell the slightest difference between them. The colour and clarity were just the same. The old mixture had passed the freezer test earlier with no problem so I think next time I will just add new inhibitor & save a lot of work.

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So rather than change the whole coolant with a new mixture, could we just remove a small amount and replace with central heating inhibitor as sold by the likes of Screwfix? The same goes for the boat central heating system which also needs antifreeze and corrosion inhibitor.

 

I wouldn't start mixing antifreeze & inhibitor. You don't know what sort of chemical reaction you will induce. For example mixing blue antifreeze with red is supposed to thicken and gel the mixture which is not what you want at all. If you want longer corrosion prevention just drain and flush out the blue antifreeze and replace with red which is meant to have a minimum 5 year corrosion protection.

 

Edit: I hadn't seen Ankorsol before but as it says it's compatible with both types of antifreeze it's probably the answer. I might get some myself.

Edited by blackrose
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I wouldn't start mixing antifreeze & inhibitor. You don't know what sort of chemical reaction you will induce. For example mixing blue antifreeze with red is supposed to thicken and gel the mixture which is not what you want at all. If you want longer corrosion prevention just drain and flush out the blue antifreeze and replace with red which is meant to have a minimum 5 year corrosion protection.

 

Edit: I hadn't seen Ankorsol before but as it says it's compatible with both types of antifreeze it's probably the answer. I might get some myself.

 

Red (OAT) antifreeze is fine in modern engines built after the mid 1990s, and which will probably have been designed to use it, but if you have an older engine which recommended blue ethylene glycol antifreeze antifreeze, I suggest that you continue to use blue, but make sure it contains silicates.

 

There have been several published examples of red antifreeze damaging the engine seals in MG classic cars, causing them to leak (and require new seals fitted). The OP does not state which engine he has, but anyone with an older engine such as the ubiquitous BMC 1.5/1.8 should continue to use blue antifreeze.

Edited by David Schweizer
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Recently after 9 years in service I thought it about time I did something with the antifreeze in my engine and central heating. I decided to replace the lot with like for like blue glycol. I drained 30 Ltrs from the engine cooling system and 12 Ltrs central heating. Having mixed the new antifreeze to refill the systems I compared it with the old I had removed and could not tell the slightest difference between them. The colour and clarity were just the same. The old mixture had passed the freezer test earlier with no problem so I think next time I will just add new inhibitor & save a lot of work.

Glycol based antifreeze will retain its antifreeze properties indefinitely unless the system has leaked and been topped up with fresh water. However the anticorrosion chemicals last only until they are used up, which is dependent upon temperature and types of metals used in the system.

 

Commercial chilled water systems often have external pipework, and are protected just by a water/30% Glycol mix. No corrosion inhibitors are used, but there again the pipework walls again really usually 4mm thick.

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I did ask Morris about ankersol. They said they couldn't recommend adding it to exsisting antifreeze as they couldn't guarantee if it would work.

 

Personally I know it's an expense and a pain to change all the coolant but it's cheaper than having a core plug fail as you are approaching a weir.......

 

Gareth.

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