I am building a new home (starting in 60 days) and just received a bid from a local Trane contractor. He included 3 options for this split system. One of the options was for a TXV. Through previous information on this site I have decided to include this option (local utility rebate also requires a TXV on this system). The other option is for an April Aire filter system. I'm still trying to decide about this one.

The last option was for a for something called "Tight Ducts". Not trying to be a smart alec but I assumed all ducts would be tight (not leak, that is). I'm going to call the contractor tomorrow and ask him what "tight ducts" means but I thought I would try to educate myself on the important issues relating to ductwork. Reading many posts on this site has convined me that proper duct work design and installation is one of the most important and often over looked aspects of a good HVAC job. I've also read something about a Manual D(?) calculation relating to duct work.

What sort of questions should I ask as far as quality ductwork is concerned? What are "Tight Ducts"?

Thanks very much.