Hot water tank - engine or cooling loop?

[B25Matt]

Question about installing a hot water tank. I have a heat exchange system and was wondering which engine cooling loop to hook it up to, the fresh water or engine coolant.

I've been looking for a definitive answer but can't find one anywhere.

The engine coolant loop seems the obvious choice but doesn't the coolant temperature hover somewhere close to the boiling of water? On vehicles they do at least.

[Sailmonkey]

You hook to the coolant loop. The raw water will take eons to heat the water in the water heater, and the salt will play hell with the heat exchanger in the coolant loop.

Where you attach to will depend on your engine.

[a64pilot]

My engine thermostat is I believe 180F and I think that is fairly standard, however it runs about 150 to 160 at a 2000 RPM cruise.
However if that is too hot for you, there are mixing valves that mix cold with the hot to Cool the water down.
I see it as unnecessary, I’m smart enough to not put my hand in the fire on the stove, and smart enough to not scald myself with hot water, but maybe if there are children, then I can see the need for a mixing valve.

Average modern auto is 195F, older cars used to run cooler like our boats. I believe emissions is the reason for higher temps in newer cars.
My old MG used to have two different thermostat temps, a Summer and a Winter one just as a reference