I've recently had a problem with ice building up on my plumbing stack. I've tried to do some research on my own and haven't found any information pertaining to my specific problem. I discovered the problem the other morning while working in my basement. I've had an ongoing basement renovation and noticed that there was a small pool of water on the floor directly below one of the drains for the main floor. I took a look at the drain and noticed water built up around one of the fittings so assumed that somehow the fitting wasn't glued properly. I kept an eye on it the rest of the day and was surprised to see that the leak didn't continue. The next morning i got up and checked it again and noticed that there was ice frozen to the bottom of the drain, we've had a stretch of -30 C temperatures and my basement was partially uninsulated and had only one small heater in it. I assumed that this was caused by condensation from the cold basement and the warm upper level so I finished insulating and installed another space heater to make sure that the basement never dropped below +7 C but again the same problem with water again. I've cut out the drywall around the stack on the main floor and found more ice build up on the outside, it isn't an exterior wall and the air around the vent can't be cold enough to freeze water. Anyways, I thought I'd give you all the info to date to better understand my next question. Recently, I had plumbers rough in a wet bar and laundry room. i didn't have the necessary slope to install a drain below grade so I had to use a grey water pump. The pump wouldn't work properly with cheater vents so they had to run a new vent for the pump, laundry, and bar area out the exterior and up the side of the house. Is it possible that by doing this the plumber changed the pressure so that now the main stack is constantly sucking in cold air from outside causing condensation to form then freeze on the outside of the vent overnight and ultimately melt the next morning when we start running the hot water?
Any insight would be much appreciated, thank you
Joel in northern Ontario