A comparison of the NVT and NVE ensemble simulations of tetraglyme showed that, in terms of energy, temperature and most of the structural features the results were very similar. However, major differences were observed in dynamic properties, ie in the mean square displacement and in the O-O distances. A fast equilibration method suitable for amorphous polymer systems is also detailed. This was accomplished by the reassignment of the velocity distribution to the particles, after the interruption of an NVE simulation.