Rinnai Replacement Surge Protector 26i/E The Rinnai Replacement Surge Protector 26i/E water heater is a genuine electrical safeguard designed specifically to look after the inner workings of Rinnai continuous flow water heaters from nasty voltage spikes and electrical power surges. Chucked in the heart of the control system, this surge protection module is a vital part of the water heater's electronics and makes sure you've got a stable power supply to the PCB, transformer, and all the internal circuitry - just the sort of thing you want when you're running a water heater. In the Rinnai Infinity 26i and E-series models, the surge protector is stuck as a wee sub-PCB near the main control board and forms a crucial part of the power input protection circuit. If power is coming in but not coming out of the surge protector, then it's quite possible it needs replacing.