Obox WWHRS : how does it work ?
Without obox, you throw your drain water... while it's still hot ! For a shower, your tap mixes a third of cold water with two thirds of hot water, i.e. you use 40 L of hot water for a 60 L shower. … and your water heater is filled with cold water as you use its hot water.
But obox captures this heat to preheat the cold water ! As the cold water gets preheated, your tap now only need 19 L of hot water to provide you 60 L of 40 °C shower water. … and your water heater is filled with preheated water !
Without obox, you throw your drain water... while it's still hot ! For a shower, your tap mixes a third of cold water with two thirds of hot water, i.e. you use 40 L of hot water for a 60 L shower. … and your water heater is filled with cold water as you use its hot water.
The Centre Scientifique et Technique du Bâtiment (public french lab) has tested obox in 2010, 2011, 2012 et 2013. Download its test report here.