A method of delivering hot water to a water fixture in which a supplemental hot water heater is installed before the cold water inlet of a tankless hot water heater. The supplemental hot water heater is used to recirculate heated water through the tankless hot water heater at a flow rate below the minimum flow rate of the tankless hot water heater (the flow rate at which the tankless heater's heating element is activated) so that water entering the tankless hot water heater is pre-heated by the supplemental hot water heater without activating the heating element of the tankless hot water heater.