Surface condensers work indirectly, steam gives up heat to one surface of the condenser gives while a coolant such as water or air absorbs that heat from the other.  Direct contact condensers” have no intermediary surfaces; the steam and coolant (usually water) directly contact each other although a heat exchanger may eventually cool the resulting mixture. Direct Contact Condensers Jet condensers are direct contact condensers which spray a jet of cooling water into the steam to be condensed.  One of the earliest types (to right) is little more than a perforated horizontal pan inside the upper portion of a metal box. Pumping water into the pan causes a shower, condensing steam admitted to the space below.  This condensation causes a vacuum which is maintained by a vacuum pump that removes air and other non- condensable gasses liberated from the steam, a water pump removes the condensate against the resulting vacuum Possibly the most common jet condenser is the ejector condenser, ejectors being a type of “jet pump”.  A nozzle accelerates a moving stream of water, directing it through an enclosed cavity through which the exhaust steam is admitted.  The moving water entraps the steam, and any resident air, carrying them out the discharge nozzle.   Ejector condensers are compact and need no air or vacuum pump, the fluid flow itself removing entrained air.  Ejector condensers may reduce engine output because the engine must supply the power to pump the fluid flow. SACA member John Wetz took the unusual step of converting an automotive radiator into a direct contact, rather than a surface condenser.  While his radiator is not suitable for vacuum condensing, it is affordable and apparently effective.  A hose connecting the upper and lower radiator manifolds facilitates circulation by serving as a downcomer, a tee in the hose supplies water to the boiler feed pump.  Steam is admitted evenly across the lower manifold from within a perforated pipe.   The steam bubbles rise through the water columns in the finned radiator tubes and condense on contact with the surrounding water.  The cooled condensate spills over into the upper manifold into the downcomer hose, some of the condensate being drawn back to the boiler by the feed water pump and the rest free to sink to the lower manifold and establish a natural circulation.