Hi all:

I recently bought a 3 storey house + basement house. I have a gas
furnace in the basement for heating. On the third floor of the house
there are 4 air ducts which have hot air blowing with a good flow from
them. There is a room below this one on the second floor where there is
a air duct but no air is coming from it at all. Howeve in the other
rooms on the second floor the air s coing with a good flow from all the
vents. Similarly there is a kitchen on the first floor and there is one
vent directly below the room on the second floor where there is an air
duct but there is no air coming from the air vent. However there are
other vents on the first floor where the air is coming in properly from
the air vents.

I noticed that on the second floor, in one of the ducts (which works)
there is a string attached to something down in the duct.

My questions a
(1) What could be the reson that there is no air coming from the one
vent on the second floor and also from the vent directly beneath it on
the first floor? Is it possible that the previous owners from whom I
bought the house installed the ducts but never connected the ducts to
some main air pipe?

(2) What is that string in the duct used for?

(3) Who do I call to fix this? A general contractor or a furnace guy or
???


Thanks,
Goadude