We have several mentions of airships venting hydrogen to keep a certain level of buoyancy, but there's one piece of historical equipment not mentioned in the books. Obviously venting will be needed to land, but to keep normal trim during flight without having to vent gas, airships have used condensers to recover water from exhausted combustion gases for use as ballast. Obviously, similar condensers would be useful to recover water from steam exhaust both from the onboard Praegers as well as steam engines on terrestrial vessels.
Note that such condensers would also provide an additional reason to develop the talked about system of fueling the on board Praegers from the on board hydrogen as the combustion gases would be sufficiently pure water as to be used for the water feed for the Praegers as well as ballast.
