Two ICRF heating schemes proposed for the half-field operation phase of ITER in Hydrogen plasmas - fundamental H majority and 2nd harmonic 3He ICRF heating - were recently investigated in JET. Although the same magnetic field and RF frequencies (f 42MHz and f 52MHz, respectively) were used, the density and particularly the plasma temperature were lower than those expected in the initial phase of ITER. Modest heating efficiencies (<40%) with dominant electron heating were found for both scenarios and enhanced plasma-wall interaction manifested by high radiation losses and relatively large impurity content in the plasma was observed. This effect was stronger in the 3He ICRF heating case than in the H majority heating experiments and it was verified that concentrations as high as ~20% are necessary to observe significant ion heating in this case. The RF acceleration of the heated ions was modest in both cases, although a small fraction of the 3He ions reached about 260keV in the 2nd harmonic 3He heating experiments when 5MW of ICRF power was applied. Considerable RF acceleration of Deuterium beam ions was also observed in some discharges of the 3He heating experiments (where both the 2nd and 3rd harmonic ion cyclotron resonance layers of the D ions are inside the plasma) whilst it was practically absent in the majority Hydrogen heating scenario. While hints of improved RF heating efficiency as function of the plasma temperature and plasma dilution (with 4He) were confirmed in the H majority case, the 3He concentration was the main handle on the heating efficiency in the 2nd harmonic 3He heating scenario.