zalman recommend filling it around 80% of the way to the top, or around 2 litres worth of water. if you use this data and go through the calculations you find that you can expect a volume increase of about 3 mL, that's the size of a few peas. not sure how you came to conclude that no amount of stretching of the tubes can accomodate this extra volume, it seems well within the bounds of the tubes stretching to me.Tibors wrote:The Reserator contains a large volume of water. No amount of stretching of the tubes can "absorb" the extra volume if all this water is heated. So this pressure is released by the air escaping through that little hole.
regardless, water may be essentially incompressible, but if you are leaving 20% pocket of air at the top of the reserator, then even if it was a sealed system this little pocket of air would easily decrease in volume to accomodate.
the little hole has got to be for something else...!
maybe to let all the little organisms in so you can grow a friendly little mould community in there?