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paganman
paganman

Posted: Sat Aug 09, 2008 4:04pm

Post Subject: Heating system

I have just bought an ex hire boat but can't get the heating system to work. The yard I bought it from said that it is a pressurised system which works under gravity and doesnt need a pump! Sounds very dubious! I have filled the header tank but still no heat, could the system need bleeding and should i fill it with an antifreeze/wate mixture?

Tony-B
Tony-B

Posted: Sat Aug 09, 2008 6:01pm

Post Subject: Heating system

Loads of hire boats up until the early 90s used an Ellis (or an equivalent) gas boiler. This did work by gravity and had a header tank, but was NOT pressurised. You can tell if it is a gravity system by looking at the circulating pipes. If they both the hot & return run at floor level it is NOT a gravity system. If they are less than 1 inch in diameter it is NOT a gravity system. If the pipes are 15 or 22mm then it should be a pumped system - wherever they are run. A Ellis boiler is a black thing about 9 or 10 inches square and perhaps 2.5 feet tall with the flue coming from the top and the gas controls, plus window through which you can look at the burner flame, on the front. All controlling is done low down on the front of the boiler. If the boiler is about 5 ft tall and perhaps 5 inches wide and 8 inches deep with the controls about half way up the front, plus the header tank behind a cover, right at the top then it is an Alde boiler and these are not gravity. You would have removed the motor and pump to top up the header tank. This could be fitted with a room thermostat that has a switch on it as well. If you do not turn that switch on the pump will not work although you can ignite the boiler and the header tank will get hot. If the roomstat is set too low the pump will not run even if that switch is turned on. Now we come to the Eberpacher/Mikuni/Wabasto type systems. These run on diesel and may or may not be pressurised. Non-pressurised ones use a header tank, but I have seen one system, installed by a domestic central heating engineer, that used two pressure vessels like you may have in a combi-boiler at home. These are pressurised but as you seem to have found a header tank I doubt you have this system. All of this type of heater have a control, box and have to go through an automatic start sequence. They can often shut down part way through this sequence for no reason obvious to the end user, so are you sure the boiler is actually running. There are a few other gas systems but the main ones are as described above. One thing that is common across all the systems is that if you do not mix the required antifreeze (50%) and water BEFORE adding it to the system the hot antifreeze is more dense than cold water so only the pipes get hot, not the radiators. Check for that. The radiators should be bled like ordinary domestic ones, but keep an eye on the header tank level. If you can tell us more about your system I may be able to help you a bit more. Tony Brooks

paganman
paganman

Posted: Mon Aug 11, 2008 2:11pm

Post Subject: Heating system

Thank you for your prompt reply! I have checked the system and the boiler is an Ellis and son as you guessed. it ignites without a problem but the water in the tank doesnt heat up. I have therefore turned it off for safety reasons as I don't know if it is heating an empty boiler! The header tank has what looks like a pressure cap. does that help? Cheers Ivan

Tony-B
Tony-B

Posted: Mon Aug 11, 2008 3:14pm

Post Subject: Heating system

Dear Ivan, I am getting a bit concerned about this because there is no reason for an Ellis to have a pressure cap on the header tank. I assume by pressure cap you mean something like a car's radiator filler cap. However there was a move to use a small car expansion tank, fitted with a 21 psi pressure cap as the calorifier pressure relief system and this has nothing to do with the heating system. Please follow the pipe from the expansion tank and make sure it connected to one of the large pipes connected to the boiler. If it connects to a smaller pipe it is probably a calorifier expansion vessel and you need to find the Ellis one. Boiler expansion tanks are usually large, say about 2 inches thick, 10 inches long and 8 inches tall (dimensions from my Ellis). As long as the boiler has water in it there should be no reason to turn the gas off because the boiler has a thermostat on it that shuts the main burner off when the water inside is at the temperature you set on the dial. Are you sure that your main burner ignites and that you are not just looking at the pilot light? My boat had a big red lever that isolated the radiators from the calorifier and boiler so you could use the boiler to get hot water in the summer without the radiators getting hot - do you have one that is turned off. If there is a pair of Ts on the big pipes at the back of the boiler start searching the top pipe towards the first radiator. Loosen a joint on the high large pipe close to the boiler and wiggle it. If water leaks out you know the boiler is full of water. Tighten the joint and the set the boiler to maximum. Keep feeling the top pipe to see how far along the heat travels. As long as heat is moving towards the front of the boat just wait because you may still have antifreeze laying in bottom pipe and running the boiler at maximum MIGHT just get it into the bottom of some radiators. If the top pipe does not have heat travelling along it the system must be blocked by either a valve, dirt or air. Tony Brooks

Tony-B
Tony-B

Posted: Sun Aug 17, 2008 5:25pm

Post Subject: Heating system

I was hoping to have heard how you are getting on by now. Just a further thought. If this is an ex Viking Afloat boat with a Bukh engine I may be able to explain how to use the engine to heat the calorifier. Tony Brooks

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