John from Mississauga, Ontario writes: "I would like to open up a wall between my kitchen and dining room, but there is a cold air return in the way. Is there an easy way to re-route the cold air return so I can still open up this wall?"
Actually this could be a non-problem. In the drawing I showed a two story house, but imagine the bottom to be the basement with the furnace and ducting. Right now that cold air return just barely goes up into the wall and out on one or both sides to pick up the return air. When you remove the wall you can simply put a decorative floor grill right over what is left of the duct and the air in the room will flow from the hot air grills at the outside, up and then down the centre. That actually is a very good air flow. So if you can decorate to have a grill between the two floor spaces, just do that.
If you have to move the duct over, do so in the basement but do not move it close to the hot air grills or you will create a short circuit and the hot air will just return to the furnace without going through the room.