I.e is there a single route going up and down each column, or does it travel along the top/bottom left to right. My radiator has twenty set of three columns, would be good to see the inside of such a radiator.


diagram of water flow inside a pressed steel radiator Source: Paperblog

diagram of water flow inside a steel column radiator Source: Chest Of Books

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  • Thankyou, so they can go anyway they want if connected from bottom I suppose you would expect top of the complete radiator to heat up before the bottom (as long as no air in radiator) since cold water is denser ? – Paul Taylor Dec 3 '17 at 18:13

Hot water radiators which are connected together on both the top and bottom have no baffles or plugs. Inside the radiator is one open cave from end to end. The recommended way to pipe a cast iron radiator is hot in at the top and return (cold ), out the bottom. As the water cools in the radiator the water gets more dense and heavier causing the flow to be towards the bottom of the radiator. If you are interested in radiator construction you could buy or find an old radiator and take it apart.

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  • mine are new steel column radiators rather than cast iron, both ionput and output are at bottom. I would rather someone could just show me their internal construction – Paul Taylor Dec 3 '17 at 15:37
  • @RedGrittyBrick just posted pictures of what a cast iron or steel radiator looks like inside. Now, if yours do not look like the picture , then you may not have a radiator but my have a convector or baseboard radiation. Newer variations of radiators have been produced, but they are all basically the same inside.Depending on the actual construction and design, the piping inlet and outlet may not always be in at the top and out at the bottom. – d.george Dec 5 '17 at 11:43

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