My memory tricked me, when, in our discussions yesterday, I referred to THREE 3" PVC vents protruding through the roof. There are in fact only TWO such PVC vents, one having been installed by the plumber, the other 3" PVC vent having been installed by yourself to occlude an open rubber-rimmed fitting from which the plumber had removed a 3" PVC vent, but leaving an opening in the roof which he had not closed. The PVC pipe you installed to fit into this opening, you then plugged with a toilet plunger. This 3" PVC pipe should be capped with a 3" PVC cap if it is not to be used to vent a propane gas fired appliance such as a propane gas fired fireplace, hot water heater, or furnace.

The third pipe through the roof is NOT a PVC pipe at all, but a 4" metal chimney which is capped with a shield to occlude rain. The shield occludes rain only imperfectly, hence the 5 gallon bucket in the second floor closet. This 4" metal chimney pipe should be extended into the closet, with the extension protruding through the blueboard, before the closet ceiling is plastered, so that water blown into the chimney in a storm will not damage the plaster.  This 4" metal chimney may be used to vent either a) an #2 oil burner in the basement, or a wood-burning fireplace, but not both.

In the basement, I saved boxes in which the parts of the installed 4" metal chimney were received. If these boxes can still be located, they should NOT be thrown out, because they bear data which will make it simpler to match the required downward extension to the chimney that has been installed.