Posted: Wed Dec 31, 2008 11:59pm

Hi Tony Was wondering if you could give me some advice again on a couple of questions, please. I have a 40 ft narrowboat which i'am fitting out myself and it has been fitted with a eberspacher heating system through a calorifier. Whilst boxing in the heating pipes one of the connections came loose and we lost some antifreeze which then dropped the level in the filler container, i saw that somebody has already asked the question on what type to put in and it was suggested that ordinary car antifreeze is fine, so this is what we used to top the system up A few months has since then passed and i was reading a Nick Billingham book on care and maintenance and i read the section on antifreeze page 79 where he says that you shouldn't use automobile antifeeze as this has ethylene glycol in it which is toxic and he suggests using a non toxic sugar solution, could you confirm which is correct as i'm a bit concerned that i might has contaminated the system with regards to the water supply for the sinks and shower, does the cold water for these come direct from the water tank or does the water go through the calorifier first. With regards to the calorifier does it hold cold water and when you turn the heating on is it heated up through the eberspacher or do you have to have the engine running, also does the eberspacher have a thermastat in. Thank you for your time. regards martin

Posted: Thu Jan 01, 2009 10:25am

Dear Martin, first of all either email me directly so I can send you much more information & a diagram (email address in my profile) or look at the water system section of the course notes that are on my website (tb-training.co.uk). I can not comment on what Mr Billingham writes - assuming your interpretation of what he says is what he meant - but I am afraid at least two of the manufacturers of that type of heater are with me on the subject. USE VEHICLE ANTIFREEZE for the CENTRAL HEATING/BOILER water. These systems contain several different metals and the important component of the antifreeze, now we tend to use plastic pipes, is the corrosion inhibitors. I doubt sugar based antifreeze would contain any! The corrosion inhibitors "use themselves up" so you should change the antifreeze every two years or 5 years depending upon type and also NEVER mix antifreeze that has a blue/green colour with one that is red/orange/purple. Stick with the same colour type. If you do as I ask you will see the engine cooling system and the Eberspacher system feed their water through different "coils" contained within the hot water cylinder. These coils totally isolate the engine and boiler water from the water you draw from the taps so unless a pipe fractures there is no chance the antifreeze will get into the domestic water. Even if a pipe did fracture the pressure in the domestic system when the pump is running (about 30psi +) would force domestic water into the system with the fracture and that would result in water pouring from either the engine of Eberspacher fillers. I suspect Mr Billingham was talking about an antifreeze suitable for use in the DOMESTIC water system - Google "potable antifreeze". I do not understand your question about where the water goes - its just like a simple conventional house system. The cold water is pumped directly from the tank to the cold taps and into the calorifier (if a hot tap is open) whilst the hot taps are fed from the water in the BODY (not the coil(s)) of the calorifier. There are all sorts of "bodges" and workarounds used when retro-fitting that type of boiler to a boat with a single coil calorifier but if your boat is fitted with a twin coil calorifier both the engine and Eberspacher will heat the water independently of each other. The calorifier is only a domestic indirect cylinder that is much stronger so it can cope with the extra water pressure. The Eberspacher must have an overheat cutout in it and I would be very surprised if it did not also have a thermostat that normally controls the maximum water temperature but without a manual I can not be 100% sure. If this boat was built since the RCD came in you should have the manual as part of the RCD documents. Tony Brooks

Posted: Thu Jan 01, 2009 11:21am

Hi Tony Thanks for the info, it all makes sense now, i will forward my email address so you can send me the info. The antifreeze in the heating system is blue and the engine is green ( beta 28 ) and all the pipe work is plastic. As for the calorifier i think it would be a twin coil but should i be able to tell by seeing how many pipes are fitted and where they come from? So am i right in saying that you dont have to have the engine running to have the heating on as its it diesel heater and to have hot water the engine has had to be running for a while in order to heat the water up? Thanks again, martin

Posted: Thu Jan 01, 2009 2:09pm

As far as the engine is concerned think of the calorifier a bit like the car heater system. You have to run for long enough to get the cooling warm hot and then you start to transfer heat to the air in the case of a car and water inside the calorifier. As time goes on the heat from the engine gradually raises the temperature of its own cooling water and thus the domestic water. I expect you would need to be running, under load, for at least half an hour before you get reasonable hot water and even then there would not be too much of it. If its a two coil calorifier the diesel heater should heat the water up on its own but it will probably be far slower than a conventional house boiler. However once its running and up to temperature the boiler should cut in and out to maintain the water temperature in the system and thus the calorifier water temperature. Running the engine and boiler together should do no damage and only allow the boiler to stay off for longer. Tony Brooks