In the field of medical dosing device filling, a propellant conditioning assembly (10) comprises an input conduit (12) to receive a propellant at a constant pressure from a propellant reservoir (102). The conditioning assembly (10) also includes a bifurcation (18) to divide the input conduit (12) into first and second conditioning conduits (20, 22). The first conditioning conduit (20) includes a cooler device (24) to selectively cool a diverted first propellant stream (26) that flows through the first conditioning conduit (20), and the second conditioning conduit (22) includes a heater device (32) to selectively heat a diverted second propellant stream (34) that flows through the second conditioning conduit (22). The conditioning assembly (10) still further includes an output conduit (44) to receive the first and second propellant streams (26, 34). The relative proportion of the first and second propellant streams (26, 34) merging in the output conduit (44) is controlled to regulate the temperature of a merged constant pressure propellant feed (46) exiting from the output conduit (44).
