Modifications were implemented on a semi-commercial air-gap membrane distillation prototype to assess experimentally any improvement in its performance. The main changes were in the air-gap domain with focus on reducing the conductive heat transfer losses by reducing the physical support that separates the membrane from the condensation surface. Moreover, several feed channel spacers were tested as well and assessed based on their effect in increasing the mass transfer and imposed pressure drop. Results show that the modifications increased slightly the distillate mass flow rate by 9-11% and reduced the conductive heat losses by 20-24%. Spacer effect was found to be mainly in imposed pressure drop within the tested types.