How can the Drainwater Heat Recovery System triple the shower-capacity
of an electric water heater?

Typically, a 40°C shower fed by 24 to 7°C water at 9 litres per minute depletes a water heater's stored energy at rates of 10 to 20 kW until the heater's upper-element is energised and these rates are reduced to 5.5 to 15.5 kW, respectively. By feeding back 4 to 10 kW (40 to 50%), the Model F-601 can further reduce these depletion rates to extend showering-times by factors of about 2.8 to 3.7.

    Will the Drainwater Heat Recovery System
also improve the performance of gas and oil water heaters?

Of course, recycling energy with the Drainwater Heat Recovery System will improve the performance of every water heater, but the improvement may not always be as dramatic as with electric heaters since modern residential gas and oil water heaters generally provide an adequate supply of hot shower water.

    What about tank-less (demand) electric and gas water heaters
that heat water instantly?

There's no stored energy in this case, but the F-601 can instantly feed back 4 to 10 kW; corresponding to 40 to 50% of the power required to sustain a continuous shower at 9 lpm. Without the Drainwater Heat Recovery System, a tankless electric water heater demands 41.5 to 83 amps at 240 volts to sustain a 10 to 20 kW shower stream. With the Drainwater Heat Recovery System, AC current demand drops by 24.9 to 41.5 amps; providing many benefits for user and utility. For example, in addition to the virtual elimination of standby-loss, electric-service requirements are cut by 16.6 to 41.5 amps and corresponding IR transmission losses -- which add to utility operating costs -- are cut by factors of 2.8 to 4!