of the spray heads 48 because a significant quantity of water is lost in the form of vented vapor it is necessary to periodically add water to the system to this end a water make up line 89 is connected from a suitable source to the conduit 84 and is provided with a liquid level conduit valve 90 the valve 90 is operated in any suitable fashion as by the provision of a float 92 having a density less than water but greater than that of the petroleum solvent being recovered the float 92 operates through any suitable control linkage 94 sealed against the vessel 66 by a suitable connector 96 as the water level 62 is lowered as naturally occurs due to the loss of vented water vapor in the spray chamber 40 the float 92 is caused to move downwardly thereby opening the valve 90 and delivering make up water into the conduit 84 as soon as the water level 62 rises to an appropriate level the float 92 acts through the linkage 94 to close the valve 90 make up water is preferably delivered into the conduit 84 rather than into the separator 60 for several reasons first the condensing efficiency in the spray chamber 40 depends to a substantial extent on the temperature of water delivered through the spray heads 48 by adding make up.