Instantaneous fluid heating device and process including an instantaneous fluid heating device which features forced fluid recirculation past/through heating elements/vessel featuring immersible electrical heating elements in a plurality of heating vessels arranged in series with all of said electrical heating elements/vessels being of equal electrical power/volume so as to be equal in overall heating capacity and receiving electricity simultaneously by on/off switching of electrical power via one or more solid state relays responsive to the minutest changes of temperature below/above the set point.
