two pipe steam trouble

Chris Petersen

I recently found myself working on a two pipe system with steam traps that were faulty most of the old ones had distorted diaphrams, i replaced the traps with new ones, however it didnt seem to cure the problem, short cycling. Here in St. Louis we have alot of one pipe systems but i am sorry to say that i am not familiar enough with a two pipe system to make an accurate diagnosis. I noted that the main air vent only releases air when the boiler shuts off, iam now wondering if the main trap is faulty. also my radiators heat all the way across but not down to the traps. i am wondering if the return has pressure in it? but from where?