Patent ID: 7206506

Claim:
A fluid heating unit comprising: a fluid heating tube assembly including a first fluid heating tube with a tube formed of heat conducting material having an inlet end, an outlet end and a flow path extending therethrough, a dielectric coating permanently bonded on an outer surface of the tube intermediate the inlet end and the outlet end, and a resistive layer formed on the dielectric coating, and a second fluid heating tube with a tube formed of heat conducting material having an inlet end, an outlet end and a flow path extending therethrough, a dielectric coating permanently bonded on an outer surface of the tube intermediate the inlet end and the outlet end, and a resistive layer formed on the dielectric coating, the inlet end of the second fluid heating tube coupled to the outlet end of the first fluid heating tube; a power distributor coupled to the fluid heating tube assembly and coupleable to a power source; a first switch coupled to the power distributor and the first fluid heating tube, the first switch movable between an open position preventing current flow to the first fluid heating tube and a closed position allowing current flow to the first fluid heating tube; and a second switch coupled to the power distributor and the second fluid heating tube, the second switch movable between an open position preventing current flow to the second fluid heating tube and a closed position allowing current flow to the second fluid heating tube.