The Tuff Electrode Phase Change Hot Water Boiler utilizes the conductive and resistive properties of water to carry electrical current and generate heat. Alternating current is introduced into the boiler drum from the outside through an insulation device, using water as a conductor to complete the energy conversion process. During operation, there is no heat accumulation or transmission loss, achieving nearly 100% conversion of electrical energy into thermal energy. By controlling conductivity and water level, the boiler’s operating power is regulated. Heat energy is transferred to the heating system via the phase change heat exchanger at the top of the boiler. The system does not require external components such as expansion tanks, circulation pumps, or first-side heat exchangers. The boiler’s internal dual-zone devices and the phase change heat exchanger at the top complete a closed loop of heating, evaporation, condensation, heat release, and reheating. This results in high heating efficiency, zero pollution, and reliable safety.