Wednesday, December 07, 2005
What Lies Beneath, the Update
That banging in the wall - it was from two large PVC pipes expanding and contracting with temperature change. The two pipes are respectively the air intake and exhaust for the gas furnace in Unit 2C. Second floor units have their HVAC systems inside their units while the 3rd and 4th floors have their HVAC on the roof. The pipes were creaking from the cooling effects of drawing in cold outside air and the expansion of the exhaust pipe from the hot gas. There is only one support along the floor holding the vertical pipes in place. There are no other supports until somewhere in the ceiling. I shimmed in some lubricated backing material to hold the pipes away from the wall as much as possible. Difficult since the tolerance is only about half a centimeter on either side. This mitigated much of the noise, but it still bangs a little bit, but not annoyingly so and not so much as to startle me in the night. Much of the noise is actually coming from inside the ceiling, and I'm not about to cut a hole into the crawlspace anytime soon. So, it'll have to wait until the association is under our control since this is a problem covered by the condo rules. As always, I'll keep you posted on further developments.