TRI-HP EU project is aiming to develop trigeneration integrated solutions that combine heating, cooling and electricity generation, based on heat pumps running with natural refrigerants and using multiple renewable energy sources. This deliverable presents the design of the R290 dual source heat pump (DSHP) prototype. The designed heat pump is reversible, includes a variable speed compressor, and a desuperheater (DSH) for domestic hot water (DHW) preparation. Its main innovation is the inclusion of a dual source heat exchanger (DSHX); able to work with water, air or both; in evaporator and condenser modes. The deliverable provides a justification of the commissioning of the test bench and testing campaign of the DSHX, starting from the design conditions previously set in the project.