solar collector 3 : the water tank 2

time to put in the tank insulation and lining.
it's essential the tank is as well insulated as possible. the more insulation the better the system works.
there are many kinds and types of insulation but there are only a few with the right properties for this application. the material has to be resistant to relative high temperatures, mechanical stress (since the tank is insulated on the inside the material will have to resist the water pressure and weight of the water) and have an as low as possible thermal conductivity.
the material of choice is polyisocynurate or PIR ; very tough with great thermal properties (it's actually twice a good an insulator as rock wool with an R-value of 8 per inch). i'm using 10 cm thick boards that should insulate the tank pretty well. PIR is not only a super material but also super rare : it was only available in ghent - a city 50 K from where i live - and it took me three hauls with our small car to get it all home. ;-)




next up is the pond lining. EPDM liner is the best quality - lasts forever and resists 135 °C - but exceedingly expensive. pvc liner doesn't last as long and is less heat resistant but it can still withstand temperatures up to 80°c (tank stays below 65°c) so it'll do the job just fine.

just cut to size and fold :-)


and of course one of the center pieces of this installation : the heat exchanger between the solar heated water in the tank and the tap water; here in the shape of a hundred meter long coil of PE tube.