I have an old steam system converted to hot water, which use steel pipe. One of the pipe nipples connecting one of the radiators is badly rusted, and appears to be leaking under the floor to the ceiling below. It leaked badly one day, and then has appeared to stop on its own. I'm hoping to wait till summer to replace this section of pipe, because I have two tenants and myself on the same heating system. What are the chances of a full rupture of this rusted pipe, leading to a sudden hi-rate of leakage? I imagine the system pressure must have increased suddenly to cause the leakage and has stayed low since.. the system is supposed to be low pressure of course.