Have a house built in 1858. I’m considering converting the current two pipe vapor steam system to a hydronic system. Need to know some of the things I should be considering. If possible, would like to retain the existing cast iron free-standing radiators. The boiler was replace 3 years ago (Burnham). Can it be converted to hydronic by adding circulators, etc.? Need advice badly. Thanks
The radiators will have to have the outlet bushings removed and full sized ones installed. You can either replace the return piping with a reverse loop hot water return, or replace the entire system with a single pipe Mono-Flo design. The radiators will have to have hot water air vents located at the top of the radiators and the steam vents, which are half way down the radiator will have to be removed and the openings plugged. You may want to replace the steam radiator valves with hot water valves, but it is not absolutely necessary. The boiler will have to be outfitted with the complete line of devices, i.e. Flo-control valve, compression tank, air eliminator, pump, burner controls, etc.
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.