I had a large old steam furnace/radiator system in a 4-unit rental house. One winter, the furnace began overfilling with water which caused the pipes to shake the whole house with extremely loud banging in the pipes.

Not too long fter replacing the electronic valve (which did not correct the problem)that furnace died. Since then, I have installed a new furnace with another new electronic regulator valve. The radiators are all the same, and most of the piping is the same, and again, the overfilling problem occurs. It does not occur until the temperature gets really cold, into the teens and below. But then the furnace overfills with water, and banging occurs to a lesser degree than before, just in one apartment right above the furnace.

I have had the original furnace installer look at it several times, and two other plumbers look at it. Nobody knows for sure what is going on. Each plumbers recommends some form of repiping, but after all the work I have had done so far to fix this problem, I am skeptical of paying someone a bunch of money for something they say MAY fix the problem, when they don't really understand what is going on.

Anybody experience something similar or have any insights that might have been overlooked?

The tenant in the one apartment also reports that just before the banging begins, his apartment gets noticeably hotter than normal.