Steam to hot water conversion

[MasterPlumbers]

I am involved in a project in which a steam heat system was replaced with a hot water system. The old radiators were re-used (they have internal connections on both top and bottom). After the system had been operating for a while, two of the radiators cracked and broke open, flooding the house. The breaks were not at joints, but in the cast iron itself, near the top of the tubes. The circulating water pressure is set at 30psi and the temperature at 120 degrees. Has anyone experienced anything like this? I should note that on all but one of the 11 radiators in the house, the bleeder valves were installed near the bottom of the radiator instead of at the top. Any thoughts on what could have happened? Thank you.

[AKPlumber]

Not sure of the exact way the conversion you speak of was done or the appliance. Assuming that you installed a new hydronic system with a BOILER, then I’ll say 30 PSI is far too high a pressure, normally in most domestic boilers the pressure is somewhere closer to between 10 to 20 PSI. Do you have a regulating valve in line with the cold supply to the boiler??

[AKPlumber]

I should add, that retaining old steam radiators in a new hydronic heating system would be ridiculous. You need new registers for the loops, fin tube type at least. I don’t understand.

[Author]

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