Optimal single electron pumps emit regular streams of particles, displaying no charge current noise. Due to the wavepacket nature of the pumped particles, the emitted energy is however fluctuating, giving rise to heat current noise. We investigate theoretically these quantum heat fluctuations, considering single particle sources implemented with edge states in the quantum Hall regime. The heat fluctuations are detected via experimentally accessible potential fluctuations in a terminal in the hot-electron regime, coupled to the source. Investigating the full statistical distribution of potential fluctuations, we find that 2n:th order correlations of the potential fluctuations provide direct information about the n:th moment of the heat fluctuations of the source.