There are two heating vents in a room upstairs and no heat or air
comes out at all.  I am fairly certain that the ducts are connected to
the heating system and it seams there is a disconnect somehwere.  Is
there a way to look inside the headting duct or otherwise determine
where the disconnect might be?  The ducts are 6" round.

Hi bubba,

I had a restaurant with a problem in plumbing. Every time we had a
'rush' or a bus came in and the bathrooms were heavily used within a
concentrated time frame we had a back up. I hired a retired plumber
who came with his 'snake' to check out the problem. From the township
office we were able to estimate the distance from the toilets to the
sewers, and when Doug ran the snake through, we came up about 6 feet
short. It turns out that when the sewer was installed MY pipes were
never connected to the sewers! They were just 'out there' connected to
nothing. Crappy workmanship, for sure.

Anyway... here's my suggestion:

If you have a plumber's snake, or can borrow or rent one, take it to
the rooms in question and run it down through the vents to see how far
it goes. You should be able to estimate the distance between the
furnace and the vent opening. If it greatly falls short of your
estimate, track down where it ends and go from there.

Hope this helps,

Regards, 
revbrenda1st

Goto your furnace and trace the lines out. At your furnace they most
likely wont be 6" round lines. They will be most likely square. Look
for a little handle sticking out of the side. These places have
"shutoffs" inside the duct. It is possible that it was shut off by
accident or on purpose as a way to control the flow to the vent
outlets. If your vents are all open then you are left with 2
possibilites. First is your furnace is not rated high enough to heat
your house. Make sure you are getting forced air from the other vent
registers and not simply gravity heat. The reason for this is your
blower fan may not be functioning properly. If you are getting forced
air anywhere then it is fine. Second thing is your ductwork may not be
connected. In this case do not use a plumbers snake. A plumbers snake
is a tool specifically designed to remove clogs in drains, not measure
distances of ductwork. You can however hire a plumber who owns a cable
with a camera in the end of it. Have them check it out. I had my sewer
looked at with this equipment and it costed about 50$. Hope this
helps.