I have an issue with a single radiator (copper fin convector in a steel enclosure) on a one-pipe steam system which I ran (yes, not a professional) several years ago to a finished sun room (former porch). I ran this radiator off an existing riser from the supply main, in a wye configuration (yes, I know that it needed a dedicated riser, but at the time, due to budgets, it was either try an improper setup or no heat in that room at all). The riser runs from my toasty basement under the fully enclosed, but not heated crawlspace of the sun room, about 7 feet, and comes up through the floor on the far side of that room (the exterior wall side). The enclosed space under the room is cinderblock, and the riser runs through a 2 x 12 bay insulated with fiberglass batt insulation, and enclosed in with 3/4 plywood and caulked. So essentially, the bottom of the room is closed and insulated, not open to the elements, but is unheated. It always took the heat longer to get to this room, and when it did (with consecutive heat cycles), it spewed water from the valve. We replaced our boiler a couple of years back, and replaced all of the valves with Gortons that were specified by Gorton technicians to achieve proper heat based on distance from the boiler. That improved the situation a bit, as more heat was sent to the sun room, and although the radiator still spewed, it did improve somewhat. A few days ago, I had my plumber cut the supply main and install a proper dedicated riser to the sun room, eliminating the wye and returning the shared line to the original line it was split from, so now there are two dedicated risers, as they should have been from the start. Unfortunately, I am still getting water coming out of the valves, and although it seems to have improved again, spewing is still spewing, and I'd like it to stop. The radiator is extremely pitched (no mistakes about that) back to the radiator valve, and the valve shoots straight down into the floor to a 45 elbow and then a pitched run of about 7 feet to the newly added riser to the main. I originally thought that the condensation from the shared line was pushing water into the radiator, so instead of it running back to the supply main, it remained or even was drawn into the radiator. Now that they're separate, I'm not sure if the water is generated by the (colder) pipe inside the sun room floor. Any thoughts or things that I can try to troubleshoot would be greatly appreciated.