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Add main vents in basement?
I have single pipe radiators on the second floor. They take a while to heat up but they do heat up. I found that I have no main vents in the basement. It would seem like there are places in the basement where they potentially should/could go but I'm no expert. The pipe with the quarter on it in the first pic, is that where there should be an air vent? Right now it's just capped off. In the last pic there's another capped of opening. Is that for an air vent? And in the second to last pic there's that opening with a plug screwed in.
Enlighten me please.