wno-1
2012-10-23 14:59:56
- #1
This is fundamentally wrong. A limescale layer around the heating elements increases the thermal resistance and thus reduces the efficiency of the boiler. This causes more energy to be required to heat the contents of the boiler because an additional thermal resistance must be overcome.What applies to gas- or oil-fired boilers, namely that a system without limescale deposits can save about 20-40% energy, does not apply to the electric boiler. While with gas or oil boilers more heat rises unused up the chimney when the heat flow is impaired by the limescale layer, the heat from an electric heating coil, which is surrounded by water all around, cannot go anywhere else but into the surrounding water. The heating process takes somewhat longer when scaled up, but the higher core temperature in the heating coil also increases the electrical resistance, which leads to a reduced power consumption.
If your example were correct, a heating coil completely isolated from the surrounding water would indeed take infinitely long to heat the water but would then consume no energy at all.