Raritan water heater connections

[hlfm]

I just replaced the original hot water tank in our Santa Cruz 2866 with new 6 gallon Raritan with heat exchanger and connected hoses from engine the same way they were on the old one

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where it says engine heating in old diagram, the top hose connection went to the front of the engine, the bottom went to the top of the engine.
The new heater has much more separate ports, and I assumed the hose coming from the front of the engine would be the supply and the return would be going to the top of the engine. But after running engine, the lower heat exchange hose heats up before the upper, which makes me think I am wrong. The supply should go to the upper port on the tank says the instructions, and if so does it make a big enough difference for me to gush coolant out again and switch them?

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[km1125]

I doubt the direction makes any difference in that application. It's just a heat exchanger sitting inside the tank.

If it was the other kind of heat exchanger, where it's basically one tube inside another tube, then direction would matter as you want to keep the temperature delta between the two flowing liquids as high as you can across the whole length. In your application, the whole heat exchanger is sitting inside the tank and there's no appreciable temperature difference from top to bottom.