The goal for the hot water was to provide all of the heating from solar collectors on the roof and wetback from the fire place. The solar hot water system is at full pressure but uses a small pump to circulate the water as the collectors are above the cylinder so the water does not naturally thermo-syphon as it would if the cylinder was higher than the collectors. The cylinder we bought has a 300 litre stainless steel core to resist the mildly acidic water experienced from ground bores and roof collection systems, 3 sets of inlets & outlets (cold in, hot out + solar in, solar out + wetback in, wetback out) as well as an internal low pressure heat exchange coil for the wetback water. This was required for the wetback water to naturally circulate using the thermo-syphon method. That's where the water becomes less dense as it heats and so tends to rise in the wetback and travel up the inclined pipe to the cylinder. At the same time, colder water falls from the lower cylinder pipe into the wetback to be heated. In addition, there are two electric heating elements in the cylinder - one half way up and one at the bottom. They are separately switched which allows us to leave the bottom one off, giving the solar and wetback some cold water to heat (which then collects in the top of the cylinder and stops the upper element from turning on provided the water remains hot enough. Update: Over the first year of operation since the build, we were able to confirm the system worked very well in winter and in summer, using only solar and wetback as I didn't turn on either electric element and monitored the temperatures daily using the solar controller. (The one time we did turn on the electric elements was when we had a huge family gathering for Christmas and needed showering for around 20 people!) What a nice clean site for set out!  "I think he'd better double check that measurement" says the junior inspector   Headers & Frames up...  Plumbing connected. The collector tubes are not installed until after the plumbing system is finished.  The beige units on the cylinder are the solar controller unit and the display unit. The inline pump is the little green unit.  Collector tubes installed.  Next Page..... 34 - Painting |