patricmaude
New Member
Does anyone have any idea what chemical I can use to descale the Fresh water cooler on my Volvo 2001
descaling heat exchanger
- Thread starter patricmaude
- Start date
savageseadog
Well-Known Member
Central heating descaler (suplhamic acid)
ColinHuggins
N/A
Scuse me, how will I know when mine needs descaling?
pappaecho
Well-Known Member
Sulphamic acid is good but not always readily available. Both citric and tartaric acids are as good and available in the UK from Chemists and similar for wine making. Citric and tartaric acids are food quality products, and so are very safe with regard to the possible ingestion after the descaling operation.
cliff
Well-Known Member
Boiler descaler is "good but not always readily available"? Suggest you go to B&Q and pick up some Fernox™ from the plumbing section or if tight for a bob or two go to a plumber's merchant and pick it up at trade price.
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"Artificial intelligence is no match for natural stupidity"
sailroom <span style="color:red">The place to auction your previously loved boatie bits</span>
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sailroom <span style="color:red">The place to auction your previously loved boatie bits</span>
patricmaude
New Member
Engine overheating at high load. If SW pump and fresh water pumps OK and thermostat working then can only be heat exchanger. If you remove one of the rubber end caps you can see scale build up on the tube plate. Mine had several tubes blocked with scale.
patricmaude
New Member
Thanks for your help . Spose I'll have to get down to B&Q then.
Danny
Well-Known Member
Think I might try some Ferrox. I've used it in my central heating system at home and I seem to remember you just leave it in the system. Do you do this with the engine cooling system or do you flush it out and refill with fresh coolant? Thanks.
cliff
Well-Known Member
Remove it after descaling and refill with antifreeze solution in fresh water cooled engines. no need to bother in a raw water cooled engine as it is flushed out anyway.
BTW the name of the stuff is Fernox™
--------------------
"Artificial intelligence is no match for natural stupidity"
sailroom <span style="color:red">The place to auction your previously loved boatie bits</span>
BTW the name of the stuff is Fernox™
--------------------
sailroom <span style="color:red">The place to auction your previously loved boatie bits</span>
VicS
Well-Known Member
While agreeing that Fernox boiler descaler is a good choce of stuff to use I must point out that Fernox is a brand name and that encompasses a wide range of products.
Do a Google for Fernox to find then all.
<u>What is needed is the acid descaler , DS-3.</u> There are other system cleaners etc which will not be effective in removing hard layers of limescale. You may not find it in the smaller DIY stores but any good plumbers merchants should have it and be able to confirm that you have the right product.
The stuff you leave in a central heating system is not what is need at all. That is a corrosion and scaling inhibitor.
There are, of course, also other brands of descaler just as there are makes of vacuum cleaners other than Hoover.
Do a Google for Fernox to find then all.
<u>What is needed is the acid descaler , DS-3.</u> There are other system cleaners etc which will not be effective in removing hard layers of limescale. You may not find it in the smaller DIY stores but any good plumbers merchants should have it and be able to confirm that you have the right product.
The stuff you leave in a central heating system is not what is need at all. That is a corrosion and scaling inhibitor.
There are, of course, also other brands of descaler just as there are makes of vacuum cleaners other than Hoover.
MedMan
Well-Known Member
I'm getting a bit confused about all this talk of 'descaling'. I'm no chemist, but isn't 'scale' the build up of calcium carbonate that you get in hard water areas? Surely it is salt - principally sodium chloride - that builds up in the heat exchanger. If so, is a 'descaling' solution the correct product to be using?
I await being educated.
I await being educated.
Danny
Well-Known Member
Thanks VicS and Cliff. Thinking about it the indirect cooling system on an engine is totally different from a central heating system. The Fernox DS-3 stuff appears to be designed to descale the 'secondary' circuit - IE the cylinder and hot water pipework to the taps, etc. (but not the boiler or radiators) whereas I want to descale the 'primary' circuit - IE the fresh water coolant circuit (not the salt water circuit) on the diesel engine.
Have I got that right? I think MedMan is wrong to think that the 'scaling' will be salt deposits. This would only occur in the salt water side of the cooling circuit. I'm assuming that we're all talking about indirectly cooled engines here.
The Fernox stuff I was thinking about goes in the 'primary' side of a central heating system and is to prevent sludge building up in radiators, boilers, etc - not the same problem at all, of course.
So - I need to use this DS-3 in appropriate solution in the cooling system; run the engine a while; then flush it all out and re fill with antifreeze solution as normal.
Do I need to completely drain the system first, or just enough to get the appropriate amount of DS-3 in?
Thanks for all the advice so far - I'm fearful of putting the wrong stuff in the wrong place and dissolving the engine instead of the scale!
Have I got that right? I think MedMan is wrong to think that the 'scaling' will be salt deposits. This would only occur in the salt water side of the cooling circuit. I'm assuming that we're all talking about indirectly cooled engines here.
The Fernox stuff I was thinking about goes in the 'primary' side of a central heating system and is to prevent sludge building up in radiators, boilers, etc - not the same problem at all, of course.
So - I need to use this DS-3 in appropriate solution in the cooling system; run the engine a while; then flush it all out and re fill with antifreeze solution as normal.
Do I need to completely drain the system first, or just enough to get the appropriate amount of DS-3 in?
Thanks for all the advice so far - I'm fearful of putting the wrong stuff in the wrong place and dissolving the engine instead of the scale!
VicS
Well-Known Member
Sea water contains high concentrations of calcium and magnesium, which are resposible for "hardness" in water.
The scale formation is due to the decomposition of the bicarbonates of these. It is the bicarbonates that give rise to what is know as "temporary hardness" which may be defined as the harndness which can be removed by boiling (being removed as their carbonates).
The remaining hardness is termed "permanent hardness" and is due to other salts, mainly sulphate.
In a nut shell, sea water is high in temporary hardness and will therefore deposit limescale (as you say calcium and magnesium carbonates) when heated. The only effective way of removing carbonates is with an acid solution. Central heating boiler descalers are based on weak organic acids such as citric acid or on sulphamic acid none of which will do damage to the heat exchanger itself.
If the deposits were just due to salt then they could easily be flushed away with warm water.
I hope that makes things a bit clearer. Despite my advancing years I have remembered a bit of 'O' level chemistry
The scale formation is due to the decomposition of the bicarbonates of these. It is the bicarbonates that give rise to what is know as "temporary hardness" which may be defined as the harndness which can be removed by boiling (being removed as their carbonates).
The remaining hardness is termed "permanent hardness" and is due to other salts, mainly sulphate.
In a nut shell, sea water is high in temporary hardness and will therefore deposit limescale (as you say calcium and magnesium carbonates) when heated. The only effective way of removing carbonates is with an acid solution. Central heating boiler descalers are based on weak organic acids such as citric acid or on sulphamic acid none of which will do damage to the heat exchanger itself.
If the deposits were just due to salt then they could easily be flushed away with warm water.
I hope that makes things a bit clearer. Despite my advancing years I have remembered a bit of 'O' level chemistry
Danny
Well-Known Member
Arrggh! Now you've confused me again. You seem to be suggesting that the scale buildup is due to the sea water! I thought the sulphamic acid (DS-3 or whatever) was used in the fresh water side of the system.
Maybe you could give me a step-by-step of the process you use? (Sorry to be a nuisance)
Maybe you could give me a step-by-step of the process you use? (Sorry to be a nuisance)
VicS
Well-Known Member
I am surprised that the fresh water side of the system should need descaling. It must have been drained and refilled many times with very hard water for that to happen and the place where the scale build up will be greatest will be in the engine itself rather than the heat exchanger.
Assuming you are correct about the scaling then yes use something like DS-3 but work out the right sort of amount needed based on the capacity of the system. I would definitely drain the old coolant off first and refill using the descalant pre-dissolved in the water (warmed, or even hot, preferably). Yes run the engine a bit to circulate the solution and keep it warm. Afterwards I would drain & flush the system thoroughly, perhaps even adding some sodium bicarbonate to neutralise the acids (Washing soda, sodium carbonate, even but don't stew aluminium components in washing soda for too long). Drain from all the engine drain cocks or plugs at each stage. Finally refill with an antifreeze mixture and don't drain it too often.
If the seawater side of the heat exchanger needs descaling then it is probably better/ more convenient to remove it and just soak it in the descaling solution until clean. You could do that if it is just the fresh water side that needs descaling but I am sure that if it does then the engine will be in greater need of descaling.
The reason to recommend a boiler descaler rather than the hydrochloric acid based brick cleaners is that being being based on weak acids they are far less likely to do any damage to the engine and other parts of the system. (The term 'weak' has a specific meaning in chemistry, quite different from dilute.)
BTW your references to the primary and secondary circuits in a central heating system are a bit muddled. The primary circuit is the boiler, the radiators, the pipework and the inside of the heating coil in the hot water tank. The secondary circuit is the domestic hot water itself, ie what you bath and wash up in!
Assuming you are correct about the scaling then yes use something like DS-3 but work out the right sort of amount needed based on the capacity of the system. I would definitely drain the old coolant off first and refill using the descalant pre-dissolved in the water (warmed, or even hot, preferably). Yes run the engine a bit to circulate the solution and keep it warm. Afterwards I would drain & flush the system thoroughly, perhaps even adding some sodium bicarbonate to neutralise the acids (Washing soda, sodium carbonate, even but don't stew aluminium components in washing soda for too long). Drain from all the engine drain cocks or plugs at each stage. Finally refill with an antifreeze mixture and don't drain it too often.
If the seawater side of the heat exchanger needs descaling then it is probably better/ more convenient to remove it and just soak it in the descaling solution until clean. You could do that if it is just the fresh water side that needs descaling but I am sure that if it does then the engine will be in greater need of descaling.
The reason to recommend a boiler descaler rather than the hydrochloric acid based brick cleaners is that being being based on weak acids they are far less likely to do any damage to the engine and other parts of the system. (The term 'weak' has a specific meaning in chemistry, quite different from dilute.)
BTW your references to the primary and secondary circuits in a central heating system are a bit muddled. The primary circuit is the boiler, the radiators, the pipework and the inside of the heating coil in the hot water tank. The secondary circuit is the domestic hot water itself, ie what you bath and wash up in!
VicS
Well-Known Member
At the risk of posts crossing again.
If you are talking about descaling becase you think the performance of the heat exchanger is poor then it is far more likely to be scaling on the seawater side. As already indcated severe scaling on the fresh water side would surprise me.
Whichever, boiler descaler is the stuff to use in my opinion for the reasons I have given.
If you are talking about descaling becase you think the performance of the heat exchanger is poor then it is far more likely to be scaling on the seawater side. As already indcated severe scaling on the fresh water side would surprise me.
Whichever, boiler descaler is the stuff to use in my opinion for the reasons I have given.
Danny
Well-Known Member
Thanks for all the info.
Re:[ QUOTE ]
your references to the primary and secondary circuits in a central heating system are a bit muddled. The primary circuit is the boiler, the radiators, the pipework and the inside of the heating coil in the hot water tank. The secondary circuit is the domestic hot water itself, ie what you bath and wash up in!
[/ QUOTE ] I though that was what I said - it's certainly what I meant!
Re whether it's the primary or secondary side that needs descaling: I see your point about it being unlikely that the fresh water side scales up as this water is there all season and can only precipitate the CaCO3 that was in in it in the first place. I only assumed it was likely to be the fresh water side as this is what Cliff seemed to suggest from his post: [ QUOTE ]
Remove it after descaling and refill with antifreeze solution in fresh water cooled engines. no need to bother in a raw water cooled engine as it is flushed out anyway.
[/ QUOTE ] Guess I need to check inside the end caps, etc. to see exactly where (and if) I have the problem. The only reason I'm looking at this is that my T90 has a tendancy to overheat slightly when I go above my usual cruising speed (abt 1700 rpm). Both pumps appear OK but I didn't check the thermostat yet (not sure how to do this. Maybe heat it up in water with a thermometer in it? I guess I could just change it. I have a spare.)
Re:[ QUOTE ]
your references to the primary and secondary circuits in a central heating system are a bit muddled. The primary circuit is the boiler, the radiators, the pipework and the inside of the heating coil in the hot water tank. The secondary circuit is the domestic hot water itself, ie what you bath and wash up in!
[/ QUOTE ] I though that was what I said - it's certainly what I meant!
Re whether it's the primary or secondary side that needs descaling: I see your point about it being unlikely that the fresh water side scales up as this water is there all season and can only precipitate the CaCO3 that was in in it in the first place. I only assumed it was likely to be the fresh water side as this is what Cliff seemed to suggest from his post: [ QUOTE ]
Remove it after descaling and refill with antifreeze solution in fresh water cooled engines. no need to bother in a raw water cooled engine as it is flushed out anyway.
[/ QUOTE ] Guess I need to check inside the end caps, etc. to see exactly where (and if) I have the problem. The only reason I'm looking at this is that my T90 has a tendancy to overheat slightly when I go above my usual cruising speed (abt 1700 rpm). Both pumps appear OK but I didn't check the thermostat yet (not sure how to do this. Maybe heat it up in water with a thermometer in it? I guess I could just change it. I have a spare.)
VicS
Well-Known Member
[ QUOTE ]
I didn't check the thermostat yet (not sure how to do this. Maybe heat it up in water with a thermometer in it?
[/ QUOTE ] Yes thatss basically it. Heat it slowly as you reach the expected opening point as it takes a while for the heat to be conducted into the capsule. The opening temperature should be marked on it, sometimes on the base of the capsule, sometimes on the flange and is the temperature at which it just starts to open. That's difficult to see sometimes so what I do is push it open a bit and trap a bit of thread under the flap then suspend it in the water by that. When it drops off the thread it has just started to open. Those that have the opening temperature maked on the flange also may have the temperature at which they open fully marked
You really need a laboratory type thermometer (or a thermocoulpe on a digital multimeter) and a laboratory beaker. Everyone has those tucked away at home somewhere don't they together with a bunsen burner, tripod and gauze?
Ok what I describe is a bit OTT but that is the way to check it accurately. Unless I say it first someone will say, "Nah just bung it in a pan of boiling water, if it opens it's OK."
I didn't check the thermostat yet (not sure how to do this. Maybe heat it up in water with a thermometer in it?
[/ QUOTE ] Yes thatss basically it. Heat it slowly as you reach the expected opening point as it takes a while for the heat to be conducted into the capsule. The opening temperature should be marked on it, sometimes on the base of the capsule, sometimes on the flange and is the temperature at which it just starts to open. That's difficult to see sometimes so what I do is push it open a bit and trap a bit of thread under the flap then suspend it in the water by that. When it drops off the thread it has just started to open. Those that have the opening temperature maked on the flange also may have the temperature at which they open fully marked
You really need a laboratory type thermometer (or a thermocoulpe on a digital multimeter) and a laboratory beaker. Everyone has those tucked away at home somewhere don't they together with a bunsen burner, tripod and gauze?
Ok what I describe is a bit OTT but that is the way to check it accurately. Unless I say it first someone will say, "Nah just bung it in a pan of boiling water, if it opens it's OK."
patricmaude
New Member
Havn't checked this post since am yesterday. The scaling in my heat exchanger is on the SEA WATER side. Fresh water side is scale free ( just the normal brown sludge). Scale is hard limescale deposited in the tubes and on the tube plates.
To clean the Sea water side involves the remoaval of the heat.
exchanger. Just diconnect both fresh water hoses and both Sea water hoses and undo clamps holding it in place. All easy enough.
Many thanks to all for your help.
To clean the Sea water side involves the remoaval of the heat.
exchanger. Just diconnect both fresh water hoses and both Sea water hoses and undo clamps holding it in place. All easy enough.
Many thanks to all for your help.
