A model for microwave heating of electron rings in the ELMO Bumpy Torus configuration is analyzed using a relativistically correct quasi-linear formulation. The spatial locations of heating by the different electron-cyclotron harmonics are calculated. The steady-state ring energy and the microwave power required to sustain the rings are determined by balancing the line-averaged heating rate against classical collisional and radiative energy loss processes. Although ring formation is generally attributed to the second harmonic electron-cyclotron resonance, the calculations show that fundamental heating also plays a critical role in ring start-up and steady state. The model predicts ring power requirements for EBT which are consistent with previous estimates.