Plumbing system
Here are the details for the plumbing system in our truck - both the water heating system, and the freshwater system.
Heating
We're plumbing a calorifier into the engine's cooling circuit so we can take advantage of the heat generated from the engine while driving. The engine coolant can reach temperatures on the plus side of 100°C, so the water in the calorifier will get very hot! What more could you want after a long day in the bush than a hot shower? A small luxury that will be greatly appreciated, no doubt!
For when the truck isn't on the move for extended periods of time, we have a small diesel powered hydronic heater - the Webasto Thermo Top D - which will heat the coolant passing through the calorifier.
To get away from the need for a separate expansion tank the auxilliary heating circuit will be permanently plumbed into the engine's circuit so that as the coolant expands when the heat increases, the radiator header tank will accommodate the increase in pressure.
We also have a matrix heater scavanged off an old Skoda coupled with a couple of pc fans to provide blown air heating for the living cell. You can buy specially made matrix fan heaters, but they cost considerably more than just hacking together your own system using a car heater matrix and some pc fans. Make sure you use high temperature resistant glue to keep the plastic fan housing from direct contact with the matrix.
Fresh water
The water we will be taking on board will no doubt come from fairly dubious sources, and in an area of the world where cholera is endemic, it is vitally important to ensure the quality of water supply.
We will have a cheap 10 micron inline filter to filter the majority of sediment and larger nasties out of our tank, and will then pass the water through a Seagull IV X-2 filter from General Ecology. Widely regarded as market leader in water treatment for the mobile market (RV, boat etc) their filters are independently certified to meet EPA Microbiological Purification Standards against cysts, bacteria & virus. It makes use of no chemicals, hold time, electricity, double processing, large storage tanks or waste-water production.
What's more is it has a 7½ litre per minute flow rate, which is enough to even feed the shower - so we will have clean water not only from the drinking tap, but the rest of the domestic water system too.
We will have an inline pump in the filler hose so we can pump water from a well or river below the level of our tank, and will require another pump with at least 30psi pressure to get the water through the main filter.
We have an accumulator which will prevent surging due to the nature of the diaphragm pump, and an expansion tank to accommodate the expansion of the water heated in the calorifier.
Finally a thermostatic mixer valve will be necessary to prevent scalding, as the calorifier can heat the water to 100°C!