Many older homes were built with air duct systems that do not meet today's standards. This is especially true of the rooms located on the second floor. Installing an air duct in a room, or even in a new addition, is done with some simple tools and patience.
Size of Air Ducts
When installing air ducts in your home, it is very important to get the right size ductwork. If your air duct is too small, it will not provide enough heat to the room. Measure the room's square footage and then use that to determine the size duct.
You will not have one size of duct work that will reach to your room. Air ducts will come in small, easy-to-handle box shapes. When you install them, you will splice them together to interlock them. Reinforce the seams with tape to strengthen them and prevent air leaks.
As you are threading your way through the crawlspace to the addition, or through your ceiling joists, use meal hangers that will keep the ducts from moving.
The metal air ducts are going to be sharp along the edges. Working through it will require some patience. Wearing strong gloves and a long-sleeve shirt, gently place the ductwork in place.