The system is two-pipe, meaning that each radiator has a pipe leading into it and a pipe coming out. This can be converted to a water system more readily than a one-pipe system; although the change from 1 psig to 15 to 24 psig will reveal some leaks. The traps will have to be removed, and the conversion is a good time to install non-electric radiator valves, which will balance the system without further complication. Consult your boiler manufacturer for recommendations and permissions to change the boiler from steam to water.
