My kitchen was recently demolished and had someone came and removed all the
appliances and cabinets.

Above the stove top there is a range hood which has a galvanized 4" vent
pipe that exhaust to the roof.

About seven feet over there is another galvanized vent pipe, same size that
goes through the roof but I have no idea what it is for. They have already
demoed everything and they didn't remember what it was connected to. But
the location of it was where there used to be a double oven. Oven was 35
years old brand was Thermatronic by Thermador. Does an older oven need a 4"
exhaust vent? or may be it was an abandoned old vent that was not connected
to anything.

Another question. We also removed a huge refrigerator brand name Subzero
also 35 years old. This monster has a copper pipe connected to it's back
and it is not an ice maker supply feed. It routed into the wall, followed
the bottom plate and exited the house, on the outside is a trap and stopped.
It almost look like a normal air conditioning condensation drain line, but
from a refrigerator? I have owned a dozen refrigerator and never seen one
that needed a dedicated drain line.

May be I am just ignorant of these old old appliances. I want to make sure
I am doing this right.

Thanks,

MC