I have a forced air furnace in my 1 1/2 story home. There are several places in my duct work that I know are leaking air. The problem is that they are inside my walls. I can't get at them without tearing out some of my plaster.

I know they make a flexible liner for sewers that can be put in from one end, without digging up the yard. Do they make something similar for inside heating ducts? I only really have to do the ducts going to the second floor. I can reach the others from the basement.

Thanks
Bob