Hi you were luck you had to go back to your van that could of been horrible if you'd been in the room at the time. I now understand more of how these boilers work and I'm sure that the one I saw worked by heating normal water and then using that to heat the Di water in the same manner as domestic central heating worked. One thing I remember the whole place was very ineficient using many kilowatts to generate heat with then went out through the holes in the roof! Happy days NOT
