The second 2030 photo
shown is the way the engine should be plumbed... Hot water leaves the engine on the fitting toward the heat exchanger
side of the engine, and returns to the suction side of the pump
thru the fitting on the injection pump
side of the engine.
The thermostat "valve" which is shown in the drawing is supposed to open only after the engine heats up, but they were more trouble than they were worth and I would suggest not using one. But I would install ball valves in the two lines to and from the hot water tank so that it can be taken out of the circuit if necessary.
My recollection of the flow thru the QL heater is that it doesn't matter which way the antifreeze
flows into or out of the tank, as it is just a simple pipe loop inside the tank. But on the cold and hot water side, the cold water needs to enter the tank on the bottom and exit on the top... And it looks like you are plumbed correctly. The only thing that might be an issue is if the tank is higher than the engine, and then it might airlock and antifreeze
won't flow thru the heating
coil. A bleed valve might be needed if that is the case.
There should be an over pressure valve on the tank, located on the end close to the electrical
connection cover. If you look closely I think you will find it.
I can't see any reason why water should not flow when you open the tap, assuming you have pressure to the tank. It's just an empty tank.....put pressure on one fitting and water will flow out the other fitting.
I installed one of these QL heaters on my own boat
about 20 years ago, directly plumbed to a Perkins
4-108 and then a VP D2-55, and ( knock on wood) it has been trouble free that whole time. Warms up fairly quickly and easily holds temp overnight.