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Richard D
Richard D

Posted: Mon Nov 23, 2009 3:37pm

Post Subject: Heating/hot water configuration

Hi Tony, Iâm after some advice on heating/hot water setup. I have just bought a narrowboat with a Mikuni water heater, Calorifier and radiators (there is no solid fuel stove) and am not too sure how the system fits together. As far as I can see, the Mikuni works in series with the engine cooling system, sharing a common coil connection to the Calorifier. However, Iâm not sure how the radiators connect. I canât find any separate header/expansion tank that would suggest a separate water circuit for the radiators - would they somehow share the same hot water circuit or would it be a separate system? Iâm concerned that if there is a separate water circuit I need to ensure that it has the correct water/anti-freeze mixture before the weather turns cold.

Tony-B
Tony-B

Posted: Mon Nov 23, 2009 5:25pm

Post Subject: Heating/hot water configuration

Dear Richard, once you get into systems such as you describe they have probably already departed from best practise so one could find all sorts of variations on the theme. Without inspecting the boat I can not be too sure about how your setup is installed. If you are right about the engine cooling system and Mikuni sharing a common calorifier coil I would also expect at least one valve that is used to prevent the engine circulating water through the radiators when it is running. If it did this it could become uncomfortable in the summer and also dramatically prolong the time it takes for the engine to reach its running temperature on the majority of installations. I would expect the radiators to be piped as a two pipe system like most home central heating systems with the pipes to the calorifier (from the central heating system) being connected in the same way as a radiator but with longer pipe runs. If the engine header tank is part of the exhaust manifold I would have concerns about central heating water expansion emptying the engine header tank as the water cools and also I suspect a tendency for the central heating to airlock because the header tank is below the top of the radiators. If the engine header tank is large and mounted outside in the cockpit as per Black Prince hire boats then I suspect the system could work well apart from that lack of valving. If it has a large external engine header tank I suspect the cold level will almost be at the bottom of the tank, filling right up as the engine coolant and central heating water expands. I have seen systems using this type of boiler that employ two expansion vessels (similar to those found in combi-boilers)rather than a header tank but I can not see how this would work with a connection with the engine system. If you can see one or two "ball" shaped objects connected the the central heating pipework this is what you have. You should also find a typical "combi-boiler" filling loop to recharge one of them that acts as the header tank. If it is like this you will have a messy job every few years as you change the antifreeze mixture. Remember anything to do with central heating demands the antifreeze and water are mixed BEFORE being poured into the system. If you want more help I will need a comprehensive set of photos of all the system and pipes emailed to my TB-Training address. Tony Brooks

Richard D
Richard D

Posted: Tue Nov 24, 2009 4:42pm

Post Subject: Heating/hot water configuration

Thanks Tony. I will check the configuration again based on your advice and take some pictures if still unsure. Richard

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