Patent attributes
A representatively pumpless water heater system has an instantaneous water heater coupled in series with a storage water heater by piping circuitry incorporating a bypass valve and a mixing valve and useable to route pressurized incoming cold water sequentially through the instantaneous and storage type heaters. A control system (1) operates the bypass valve to cause a selectively variable portion of the incoming cold water to bypass the instantaneous heater and flow to the mixing valve, and (2) operates the mixing valve to blend the bypassed cold water with hot water exiting the storage heater to maintain a predetermined temperature of heated water exiting the system. Another system embodiment adds a directional bypass valve operable by the control system to selectively divert to the mixing valve a portion of the heated water exiting the instantaneous heater for delivery to the storage heater.
