Antifreeze for the back boiler

[MoominPapa]

The central heating system on my boat is currently drained down for frost protection. It would be much better of it could stay in use over the winter, so I'm planning to re-fill it with some kind of antifreeze. The system consists of a cast-iron back boiler, copper and plastic pipes, a calorifier coil (copper, probably) and a steel radiator. It seems to me that standard automotive antifreeze should be fine, but is there anything better?

[onthecut]

I should think automotive anti freeze is fine. It's what I used on my last back boiler system, with all the same materials you mention and there were no issues at all. Has the benefit of corrosion inhibition too. I suspect anything 'better' is just likely to come in a smaller, fancy bottle and be alot more expensive !

 

Mike.

[bottle]

I would expect it to be fine.

 

Two tips (not trying to teach you to suck eggs ), buy it from a 'motor factor' will probably be cheaper, also mix it before filling the system.

[dor]

Alde recommend a 40% glycol mix, but their tech service said an automotive antifreeze is fine. As Keith says - mix it before you refill: because of the different densities you can get a 'lump' that acts like an airlock and stops the circulation, even when pumped.

[DHutch]

Yeah, ours is bog std automotive anti freeze.

- Its not a mega stong mix, but seams to have done us fine for the last 10 years or so!

- Not sure if we did premix it as i didnt actaully do it, but deffornatly a good idea in non-pumped systems, as ours is due to the diffrence in densitys causing the antifreese to 'settle out' unless it mixed.

 

 

Daniel

[Pengalanty]

Yeah, ours is bog std automotive anti freeze.

- Its not a mega stong mix, but seams to have done us fine for the last 10 years or so!

- Not sure if we did premix it as i didnt actaully do it, but deffornatly a good idea in non-pumped systems, as ours is due to the diffrence in densitys causing the antifreese to 'settle out' unless it mixed.

Daniel

 

Hi!

 

I too have a central heating system with all the different metals and plastics.

 

I bought my inhibitor from a central heating wholesaler. It is not only an antifreeze but keeps all the "gunge" in suspension and stops it from settling at the bottom of rads. and low parts of the system.

 

If I was using automotive antifreeze, which I understand does the same thing, I would use the same as I use in my car.

Expensive compared with cheaper anti-freeze but I would only use the PINK ORGANIC ANTI-FREEZE, which has a long life expectancy in excess of 5 years and also holds everything in suspension. It doesn't act or corrode aluminum either.

 

Happy cruising for 2008. ~Allan~

[Smelly]

i used blue antifreeze with no real problem, however I mixed it too strong at first and it smelled quite bad out of my open expansion tank so tread lightly...

[blackrose]

I've got an inhibitor in my system which is supposed to prevent bacterial growth leading to blockages in the rads. I think its antifreeze properties are minimal but I live on board so that shouldn't be a problem. It's also supposed to reduce noise in the system - mine is not pumped. Perhaps I'd be better off refilling it next summer with automotive antifreeze, but does it prevent bacterial growth and what's the recommended mixture ratio? 50/50 for engines sounds too concentrated for this application.

Edited January 5, 2008 by blackrose

[blackrose]

i used blue antifreeze with no real problem, however I mixed it too strong at first and it smelled quite bad out of my open expansion tank so tread lightly...

 

Mine smelled too and I was concerned about air quality inside the boat. So I put the cap back on the header tank (a merc radiator reservoir), cut a hole in the cap, masticked a piece of car radiator hose in the hole and vented this to the outside through a brass skin fitting in the side of the boat. It certainly reduced both the smell and humidity coming out of the top of the previously open header tank. However, what i hadn't realised is that unlike something like sanitary hose for example, car radiator hose (which I also used to connect the brass system pipe to the header tank), is not a barrier hose. So I think a proportion of the inhibitor smell was actually coming through the hose. When you think about it car rad hose doesn't really need stop smells coming through for its intended application in a car's engine bay. Also the rubber hose material itself emits a smell when it gets hot but this gradually reduces over time.

Edited January 5, 2008 by blackrose

[DHutch]

Well if you want the same leval of protection, you have to go for 50/50 the same.

- However due to the large systemvolume usally present, its not uncommon to cost cut and reduce the temperture margin.

- You could also argue that inside the boat the lows wont be quite as lot, as it will retain heat tpo a degree on a day-today leval.

 

I would have thought protection to minus 10 was sufficent in the uk in a boat. but its your call at the end of the day.

 

 

Daniel

[bottle]

For concentration levels check the side of the container, it will tell you the protection it will provide.

 

30% will cover to -10° C

 

50% will cover to -20°C

 

These are not actual figures just an example, you have to guess how cold the winter will be.