Anti freeze for central heating?

[Hartlebury lad]

Hello all.

 

I have a simple engine run central heating system on the boat that supplements the log burner- 3 rads running off what seems to be a gravity fed expansion vessel. I fitted a new pump for it, and topped it up and it is now working when the engine is nice and hot, but what would folks recommend to put in it as an antifreeze agent.

 

Also, would the choice of any given antifreeze affect/inhibit the heating capability?

[nicknorman]

Hello all.

 

I have a simple engine run central heating system on the boat that supplements the log burner- 3 rads running off what seems to be a gravity fed expansion vessel. I fitted a new pump for it, and topped it up and it is now working when the engine is nice and hot, but what would folks recommend to put in it as an antifreeze agent.

 

Also, would the choice of any given antifreeze affect/inhibit the heating capability?

 

I think just ordinary glycol based antifreeze will be fine, at 25% - 33% concentration. Antifreeze does have less thermal capacity than water (i.e. It is less good at thermal transport) but this doesn't really seem to be significant below 50% concentration.

[ditchcrawler]

I think just ordinary glycol based antifreeze will be fine, at 25% - 33% concentration. Antifreeze does have less thermal capacity than water (i.e. It is less good at thermal transport) but this doesn't really seem to be significant below 50% concentration.

I would just add that you should mix it before putting it in the system, if you put it in neat in slugs then they could well lay in the bottom of the radiators and stop them getting hot

[cuthound]

When I got my boat, I flushed out the old antifreeze and replaced it with Ford 10 year antifreeze.

 

http://www.ebay.co.uk/itm/Genuine-Ford-Super-Plus-Premium-Anti-Freeze-5Ltr-Finis-Code-1931961/361564654307?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D2%26asc%3D39012%26meid%3Db2c1a4c8b16944b2893267793a90d383%26pid%3D100005%26rk%3D3%26rkt%3D18%26sd%3D231340479559

[nicknorman]

When I got my boat, I flushed out the old antifreeze and replaced it with Ford 10 year antifreeze.

http://www.ebay.co.uk/itm/Genuine-Ford-Super-Plus-Premium-Anti-Freeze-5Ltr-Finis-Code-1931961/361564654307?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D2%26asc%3D39012%26meid%3Db2c1a4c8b16944b2893267793a90d383%26pid%3D100005%26rk%3D3%26rkt%3D18%26sd%3D231340479559

It an interesting point. With cars, antifreeze has to be replaced either every couple of years (for ordinary antifreeze) or at longer intervals for the long life stuff. But of course this is not because the antifreeze properties decline, rather because the corrosion inhibitors decline. As I understood it this is due to combustion products depleting the corrosion inhibitor but thinking about it again, surely one wouldn't expect combustion products to get into the coolant?

 

But anyway the point is, do boat CH systems need active anti-corrosion agents or just anti freeze? If the latter, there is no point in replacing the coolant.

[WotEver]

... do boat CH systems need active anti-corrosion agents or just anti freeze?.

House ch systems require anti-corrosion additives to prevent (or at least inhibit) the rusting of radiators. I can't imagine that a boat would have any less need.

[cuthound]

It an interesting point. With cars, antifreeze has to be replaced either every couple of years (for ordinary antifreeze) or at longer intervals for the long life stuff. But of course this is not because the antifreeze properties decline, rather because the corrosion inhibitors decline. As I understood it this is due to combustion products depleting the corrosion inhibitor but thinking about it again, surely one wouldn't expect combustion products to get into the coolant?

But anyway the point is, do boat CH systems need active anti-corrosion agents or just anti freeze? If the latter, there is no point in replacing the coolant.

Good point, chilled water systems for data centres etc are filled with a 30% solution of glycol and deionised water, which is never again changed for the life of the system. However the pipework & valve bodies are mild steel and the cooling unit heat exchangers are aluminium, so perhaps fewer dissimilar metals (or less electrolytically reactive) than a boats heating system, which usually include aluminium and copper as well as mild steel for the radiators?

 

Edited for premature Submission!

Edited September 29, 2016 by cuthound

[nicknorman]

House ch systems require anti-corrosion additives to prevent (or at least inhibit) the rusting of radiators. I can't imagine that a boat would have any less need.

 

I think it depends on the type of water. Our house CH system doesn't have any additives and is very old, but then again we have lovely water fresh from the river Dee, just lightly flavoured with Royal pee from Balmoral some miles upstream...

Edited September 29, 2016 by nicknorman

[Joe the plumber]

I used this in my boat's system:

 

http://www.screwfix.com/p/no-nonsense-central-heating-inhibited-anti-freeze-5ltr/74586

 

As mentioned above, mix it to the correct ratio first and then add it to the system.

 

Originally I used an automotive OAT antifreeze, but then discovered it can (allegedly) damage soldered joints, so flushed it out and went for the Screwfix stuff instead. That left the problem of how to get rid of the waste antifreeze...

 

 

...it's still in bottles in my garage if anyone wants it (free!)

 

It's almost impossible to dispose of used antifreeze legitimately without considerable expense, unless anyone can advise otherwise?

Edited September 29, 2016 by Joe the plumber

[nicknorman]

I used this in my boat's system:

 

http://www.screwfix.com/p/no-nonsense-central-heating-inhibited-anti-freeze-5ltr/74586

 

As mentioned above, mix it to the correct ratio first and then add it to the system.

 

Does it have a specified life?

[Joe the plumber]

That's a darned good question Nick.

 

According to the answered question on the Screwfix site:

 

"No Nonsense Inhibitor and No Nonsense Inhibited Antifreeze can be mixed - they contain the same inhibitor package. Product shelf life in the unopened package is 36 months. In use the products could last indefinitely but it's wise to check concentrations at least every 3 years."

 

The word 'could' is a little offputting, but three years seems a decent minimum lifespan for an antifreeze.

[johnmck]

I used this.

 

https://www.plumbnation.co.uk/site/sentinel-x500-inhibited-anti-freeze---5-litre/?gclid=CjwKEAjw97K_BRCwmNTK26iM-hMSJABrkNtb280pRz0jg1yRp_GshV0JwZavD121qKnLYqOHlXsplRoCq5vw_wcB

[MissMax]

Forgot about antifreeze. Thanks or posting this thread

[Hartlebury lad]

Thanks for the help and advice everyone. Much appreciated.