I bought a new heatpump in Jan of 2007 and with that I replaced the ?runoffs? (the ones that go to each room). I couldnt replace the main ductwork at that time for financial reasons as I paid cash for the Heatpump and runoffs. So, I would like to replace the main ductwork at some point but I am not sure of the technical name of it is. Seems silly, I know, but my mom lives with me and she has breathing problems and just looking inside the ductwork from the 2 return air vents tells me that the previous owners probably let there kids put all sorts of things in the ductwork, and there is a musty smell which I am assuming is coming from an opening of some sort from under the house in the ductwork. This is located in a crawlspace and has no inuslation around it (well its there, but moisture has caused it to hang down off of it) (and yes, I know that the moisture problem needs to be fixed, I am working on that, I am just slllooooowwww.)
How much could I expect to pay someone to replace this and is it something I could do with help or better left to the professionals?
I would guess that the main run is at most 38 feet long and there are 3 runoffs on one side and 5 runoffs on the other and there are also 2 return air vents one 12 feet in and on the side of the house with the 3 runoffs (but in the middle of the width) and one of the side with 5 runoffs )and also in the middle of the width)
Also, is there a certain gauge that is needed to do this as I had asked the guy who installed the heatpump to replace it but he said he couldnt get the same gauge material as what was there) <-- and that is a story in and off itself