Today hot water is so readily available that we conveniently reach for it at the slightest chance (perhaps, too conveniently). Hot water makes up a huge portion of residential energy bills, up to 25% in more extreme cases. Invariably, the single biggest contributor to hot water use is that innocent showers that we all enjoy from time to time. Do you know that a quick 10 minute shower can squander 50 gallons of water using a conventional showerhead?
'Flash' and 'On-Demand' are just the different ways to call tankless water heaters. More significantly, on-demand tankless water heaters actually cuts down your energy costs that are used to heat water by half, and unlike the traditional tank system you get endless stream of hot water that never runs dry.