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I have a 2 pipe steam system with vents on the main only. Over the winter when we had that bitter cold spell I noticed that the large convector in the living room was only getting partially hot. I went to the basement and found that the supply pipe was hot but the return was cold. I am guessing somewhere in the convector there is a blockage. A few years back when we got the home the same problem existed with other convectors. The heating contractor added a bottle of 8 Way cleaner and had gotten a lot of mud out of the system. I think the only problem was that the mud had clogged the pressure troll pigtail and he had to clean it out with a pipe cleaner. My question is can I add the same cleaner and do it again myself or can I create a lot of other problems? I am mechanically inclined and don't think I would have any major problem.