The amount of current passed through the water of an electrode boiler depends on the:

The amount of current passed through the water of an electrode boiler is primarily influenced by the depth of the electrodes in the water. This is because the depth of the electrodes directly affects the surface area that is in contact with the water, which in turn influences the overall conductivity of the water.

When the electrodes are submerged deeper, a larger surface area can be engaged in the electrolysis process, enabling more current to pass through the water. This is critical in electrode boilers, where the heating depends on the electrical energy being converted to thermal energy within the water.

Other options relate to system components or settings that, while important for overall operation and efficiency, do not have a direct impact on the amount of current that passes through the water. The control valve setting regulates the flow of water and might influence pressure but does not directly control current. The speed of the circulating pump impacts how effectively heat can be distributed but doesn’t affect the current flow per se. Lastly, the voltage setting of the pressure control interfaces more with maintaining system pressure rather than directly affecting the current passing through the electrodes. Thus, the depth of the electrodes is the most relevant factor in determining the current through the water in an electrode boiler.