The ThermaVac unit has been designed specifically to be used in conjunction with the ThermaTech Superheated Water System, within its full temperature range. It enables the superheated water to be applied directly to a relatively flat surface within an enclosure and for the waste products to be drawn away from the substrate. Within the unit the solid waste is separated from the liquid waste and an internal automatic pump periodically transfers the waste to storage vessels for later transfer/treatment, or to a foul water drain as appropriate. For undulating surfaces and architectural profiles the recovery head can be used alongside a 'detail gun' as a means for catching and extracting the lower levels of run-off that are produced.