The spin Seebeck effect (SSE) is a relatively new phenomenon that could be harnessed for waste heat recovery. Its advantages lie with a new device architecture (compared to conventional thermoelectric generators) that would not only reduce the cost of fabrication but also enable separation of the key drivers of device efficiency: electric and thermal conductivity of certain active components. We are exploring Co_2MnSi as a potential material for SSE based devices having optimised the deposition conditions with previous PNR. Recent work has demonstrated an enhancement of the spin Seebeck effect on construction of multilayers such as {Fe_3O_4:Pt}. In this study we are investigating multilayer {Co_2MnSi:Pt} films prepared with and without an annealing step in order to reconcile differences in the observed spin Seebeck voltages.