Thermosyphoning question.

Hi All,
My question is -in a thermosyphoning system should the return pipe taking water from the top of the engine enter the top of the cooling tank below the water level in the tank or above it? I have been told that it should enter the tank below the water level so that there is a continuous circulatory system,and also that it should enter above the water level so that you can see that its working ok.Help!
Any ideas as to what is the correct method?
Any help or advice would be much appreciated.Thanks
All the best,
Kev.

The top pipe should enter the cooling tank below the water level.

Hi blue cat,
Thanks for that information - that certainly makes sense to me.
All the best,
Kev.

Hello Kev,

In our size of engines it doesnt really matter - it can be open or closed loop. All you are trying to do is let the less dense hot water rise up through the delivery pipe to the top of the hopper and the cold water being being heavier will replace it via the bottom pipe/loop - to cool your engine so its up to you Squire - the tinkling of water which will make you want to go to the loo (I'm thinking of all the pints of ale at a show)or the quiet and peace of a return top pipe below the level of water - all in all it works the same.

Best

Hamish

Hi Hamish,
Thanks for your reply, its good to know that I can do either,however I think that I will have the pipe enter below the water level in the tank - the sound of tinkling water may well lull me to sleep!!
All the best.
Kev.

For thermosyphoning to work the top pipe has to have a continuous uphill slope from the engine to the tank, the steeper the rise the better it will work but even if it is a slight rise it will still work, bottom pipe isn't so important as long as it has no "high points" that might "air lock" it will be fine. If you are running a paraffin burning engine and you need plenty of heat to vaporize the fuel then you can run it with the water level just below the top pipe as the water will boil and as doing so will still circulate, petrol and diesel engines need less heat so above the top pipe. You will need a short rubber hose to stop vibration transmitting from the engine to the tank as this will sometimes split the top of the tank.

Hi Villiers,
Thanks for the information - I had forgotten about the engine vibration and the need to use a length of rubber hose - so thanks again.
All the best,
Kev.