Next subject is tank related.
Today I was researching a bit more on pipes, fittings etc.

I have motorised ball valves for inlet and outlet of each tank. I want to make the inlet hoses 25mm for max possible flow although I may not need that too often really when we make the water through the desalinator, nevertheless I use that diameter because I have a few meters of hose I can use for the fresh water tanks. The tank inlet is 20mm.

For the drinking water I will use 19mm because foodgrade hose in 25mm is just too expensive and the tanks are smaller so I think 19mm is ok for that.

Image above shows a ball valve with a Pex fitting on the right for 16mm pex pipe and a 10mm male thread on the left which goes into the tank .. as most RV type things are small diameter the tank outlets are only 10mm, same as the breather at the top, but I have two of them on each side. I run the supply line to the pump in 16mm and will use both outlets of each tank. After the pump I plan a 16mm pipe to the calorifier as the pressure line and after that everything in 12mm. Only the shower circulation pipe is 16mm for high flow.

I use Pex for hot water throughout the van including the solar hot water circulation pipe and also the glycol lines for the connection of the heat exchangers ( heating radiators). The Pex lines are ok with the temperatures and easy to use.

The next step now is to produce all the valve control boxes (one for each tank – two valves) and the processor boxes. The processor boxes connect 8 valves, a total of 32 digital io signals and 5 tank senders. The tank senders are connected via little hub which in turn is connected to the processor box.

Will show a picture soon. Am in the process of making them …
Below is a picture of the IO extender shield I use because the Arduino does not have enough IO connections to handle the number of signals required. The extender does.