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#1 Removing silt and limescale from radiator
Posted: Sun Jan 03, 2021 12:22 pm
by eddiecross
Hi,
S1 4.2 Rad is out and on the bench.
Its old but seems sound.
While it is on the bench Ideally I would like to place it with the inlet/outlet pipes upmost and fill with some kind of descaler and leave for a few days to soak then flush out with water.
Any suggestions of what to use?
Thanks
Eddie

#2 Re: Removing silt and limescale from radiator
Posted: Sun Jan 03, 2021 12:30 pm
by christopher storey
Citric acid , available from pharmacies . Dissolve perhaps 1/2 lb , 0.25lg, in hot water , and leave in for 2 to 3 days . It will turn bright green and will do the job without harming the radiator
#3 Re: Removing silt and limescale from radiator
Posted: Sun Jan 03, 2021 1:59 pm
by cactusman
Agreed.. If your chemist does not sell it then it is readily available on line... Certainly don't use a strong mineral acid. And when you refill the system don't use tap water...crazy tip for anyone with a dehumidifier in their garage.....don't throw the water it collects away....store in a clean plastic container as it is ideal for both refilling cooling systems and washer bottles....

#4 Re: Removing silt and limescale from radiator
Posted: Sun Jan 03, 2021 5:50 pm
by eddiecross
Thanks Julian and Chris,
I googled a bit and it seems that vinegar is slightly stronger so may try that 1st.
I have collected about 6 litres so far from my de-humidifier...getting there!
Thx
Eddie
#5 Re: Removing silt and limescale from radiator
Posted: Sun Jan 03, 2021 6:30 pm
by cactusman
Yep....wine vinegar will be fine....ethanoic acid....or you can use methanoic acid...sold as kettle and bath descalant under the kilrock brand....I would dilute with warm water....one part kilrock to four parts water....not as cheap as vinegar though!
#6 Re: Removing silt and limescale from radiator
Posted: Sat Jan 09, 2021 11:37 am
by eddiecross
Hi,
Progress so far.
Tipped just under 5 litres of this vinegar neat into the rad.
Been there a couple of days so far but does't seem to be much going on.
Do I just need to be patient?
Eddie
Thx
Eddie
#7 Re: Removing silt and limescale from radiator
Posted: Sat Jan 09, 2021 11:52 am
by mgcjag
Hi Eddie...i thought that vinegar disolves lead in solder....could be wrong.....why not just take it to a rad refurbisher have it cleaned out properly and pressure tested...also i dont think all vinegars are the same acid......Steve
#8 Re: Removing silt and limescale from radiator
Posted: Sat Jan 09, 2021 12:53 pm
by christopher storey
I'll say it again : try citric acid. It has never failed with me
#9 Re: Removing silt and limescale from radiator
Posted: Sat Jan 09, 2021 1:21 pm
by Heuer
£9 for 18 sachets:
#10 Re: Removing silt and limescale from radiator
Posted: Sun Jan 10, 2021 8:20 am
by cactusman
According to oust....contains lactic acid.....citric is better......and much cheaper....5 Kilograms will cost around £15 from ebay....
#11 Re: Removing silt and limescale from radiator
Posted: Sun Jan 10, 2021 9:28 am
by Series1 Stu
Citric acid is definitely a better descaler than vinegar although both should work.
I can't sing the praises of Kilrock highly enough. I've used it quite extensively lately and find it quick, easy and reliably effective. There's something reassuring about the fizz it produces while going to work on the scale.
Of course, theses things are only effective at removing limescale (acid dissolves alkaline) so don't necessarily expect them to remove solidified sediment and sludge, which is more likely to give you cooling and circulation problems.
Regards
#12 Re: Removing silt and limescale from radiator
Posted: Sun Jan 10, 2021 9:40 am
by cactusman
Kilrock is good stuff....more.expensive though. Won't significantly affect solder joints or the metal of the rad although a gentle pressure test after a thorough flush might be wise...here a water butt might be handy.
#13 Re: Removing silt and limescale from radiator
Posted: Sun Jan 10, 2021 10:23 am
by MarekH
Series1 Stu wrote: ↑Sun Jan 10, 2021 9:28 am
Of course, theses things are only effective at removing limescale (acid dissolves alkaline) so don't necessarily expect them to remove solidified sediment and sludge, which is more likely to give you cooling and circulation problems.
Not quite. Try "acid+base=salt+water". Acids don't dissolve anything. There is a chemical reaction where both the acid and base decompose and the constituents recombine in a different order. The objective is that the previously unwanted and
insoluble base is swapped into some different chemical combination
which is soluble.
Series1 Stu wrote: ↑Sun Jan 10, 2021 9:28 am
There's something reassuring about the fizz it produces while going to work on the scale.
Quite the opposite - it probably means it's acting far too fast and aggressively. I'd go for the most slow and boring substance possible.
kind regards
Marek
#14 Re: Removing silt and limescale from radiator
Posted: Sun Jan 10, 2021 11:46 am
by Series1 Stu
MarekH wrote: ↑Sun Jan 10, 2021 10:23 am
Not quite. Try "acid+base=salt+water". Acids don't dissolve anything. There is a chemical reaction where both the acid and base decompose and the constituents recombine in a different order. The objective is that the previously unwanted and
insoluble base is swapped into some different chemical combination
which is soluble.
Hi Marek
"Dissolve - become or cause to become incorporated into a liquid so as to form a solution."
I suppose I used lay terms to describe a chemical matter but, to be clear, it is quite correct to say that a descaler will not necessarily remove the sludge and sediment accumulated in a radiator.
Regards
#15 Re: Removing silt and limescale from radiator
Posted: Sun Jan 10, 2021 7:04 pm
by Geoff Allam
So, after descaling what is recommended for sediment and sludge?
#16 Re: Removing silt and limescale from radiator
Posted: Sun Jan 10, 2021 7:15 pm
by mgcjag
Dont mess about with diy home remedies...there are plenty of off the shelf radiator cleaners than wont affect the metal or solder that will clean out rust and scale....and be safe for your ali head and rubber hoses.....Steve
#17 Re: Removing silt and limescale from radiator
Posted: Sun Jan 10, 2021 8:12 pm
by cactusman
I'd agree...if the radiator is in the car and you are flushing the whole system use a proprietary engine flush....I think Eddie had his radiator on the bench though....
#18 Re: Removing silt and limescale from radiator
Posted: Sun Jan 10, 2021 10:01 pm
by eddiecross
Tipped out the vinegar today- it was a bit cloudy and some sediment came uot too but not a great deal.
I didn't flush it.
From the tops of the cooling matrix I could see, there was still some kind of scale- was soft so maybe it'll flush out.
I have ordered a bottle of Kilrock. Have refilled the rad with the old vinegar and will flush and replace with the Kilrock when it arrives and let you know.
Thanks for the advice so far.
Eddie
#19 Re: Removing silt and limescale from radiator
Posted: Mon Jan 11, 2021 9:51 am
by mgcjag
I do find it a bit odd that after all the input on this thread you have refilled with spirit vineger (acetic acid).....which is a corrisive to metal and the lead in the solder....Steve
#20 Re: Removing silt and limescale from radiator
Posted: Mon Jan 11, 2021 12:38 pm
by eddiecross
Can anyone else confirm that Steve is correct and I am damaging my radiator by filling it with Vinegar?
Thanks
Eddie