I am extremely dubious of these claims (Score 2, Insightful)

I recently researched buying an electric on-demand water heater for my own home. Such heaters consume around 10-20kW and can demand 100 amps of current, they are however very efficient (as someone else noted) and so there is little waste to squeeze out of the system (a few percent at most I expect). Using microwave generating magnetrons is likely to be less efficient imo, so it is very hard to see how this company can live up to its claims. Whether by microwave or resistive heating, the same amount of energy needs to get into the water, it is not at all like a food stove where microwave ovens are genuinely more efficient (less heat loss and only the item being cooked is heated, not the stove walls too). The reason I didn't purchase an on-demand heater is that the electric service in my house would have to be upgraded, at a cost of around $3000. A new water tank, with heater, cost $700. The microwave heater would also have this cost issue. A better way to save power (nationally) would be to have dual-band power pricing (as is done in the UK) where power used in off peak hours costs less than in peak hours -- in this case a storage tank is potentially MORE efficient than on-demand since it can shift demand to off-peak hours when there is unused capacity. In any event, I doubt that a properly insulated water tank actually loses much heat, the main advantage of on-demand is that there is a never-ending supply of hot water. Andy