solar collector 2 : the water tank 1

the first thing to construct was the water tank. the tank has to be large enough to hold about 500-1000 liters of water and insulated well enough to keep the water hot for at least a couple of days. of course the more water the tank contains the more heat you can store but also the longer it takes to heat that body of water.
this tank will hold 650-700 liters and i think that is a good size for the 4 m² collector surface i'll be using.
of-the-shelf insulated tanks can be used for this but they are very expensive. buying an ordinary stainless steel or plastic water tank and adding insulation is another option but also not very cheap or particularly easy.
i decided to go with the wooden design where you build a large wooden box or crate covered on the inside with insulation board and pond liner.


this is the finished box. its basically a cube with a size of one meter. it's build in osb with some 5*5 timber for support on the bottom and top. it's glued and screwed together and should be able to withstand the water pressure (which is at its deepest point less then 10 % above atmospheric pressure).


the other thing i did was bend the copper tubes that will go in the actual collector. you see them on display on the water tanks lid.
i decided to use continues stretches of soft copper so i would have no soldered connections or couplers in the collector decreasing the risk for leaks dramatically. it took a lot of care to bend the long pieces of copper pipe into a serpentine shape but i managed to do three without screwing up.
two of these serpentines will go in the two identical collectors i'll be building first. the third - somewhat smaller - serpentine will be used for another collector i'll be building later.