I've never seen anyone use the generator coolant loop for their domestic hot water. I would discourage the thought. If the generator is running you have AC power. Use the electric heating elements. The complexity and risk seem far too great for the very limited value of using the generator's coolant loop.

Quote Originally Posted by freds View Post
My hydronic heat storage consists of two ten gallon RV water heater tanks.



The hydronic storage can be heated by:

1. External diesel boiler at the rear of the bus.
2. Engine coolant while driving.
3. Diesel Generator coolant (not yet hooked up).
4. Electric heat.

My current project is working on the charging control logic for when I am on shore power; so, I needed too dump some capacity out of the house battery; as the house battery pack was full up from solar charging.

So I remotely fired up the inverter and turned on power to the first tank, for my first test run of a load dump situation.

Currently I have 600 watts of solar panels just leaned up against the bus, but the goal is for 3KW of solar to be mounted on the roof; so dumping excess power to hot water should be a frequent occurrence.

In a driveway surfing situation with a 120V extension cord feed; I would say after three hours you could take a shower from a dead cold bus. OK in this graphic the start point was about 65 degrees and then was around 120 after three hours. The power draw for my selected RV water heater is about 1400 watts.




At 5PM I got tired of waiting and powered up the second tank to see where it would plateau at; which turned out to be 140 degrees for my tanks. I had noticed as I was wiring these heaters up; that there was no adjustment set point for the temperature.

So anyway you can see the effect of turning on the second tank heater; as a steeper slope at the end of graph.