I have a small 700sq ft single level house and a 6 1/2' ceiling basement that is currently being finished completely. I have a cold air return at the back of my house and 1 in the middle. Part of my basement is being finished to a home theater room which is closed off and the rest is open. However my floor joists run the wrong way meaning my cold air return is too low so were hitting our heads. I want to cut it shorter by 10' and put the vent in the basement instead, leaving 1 on main level at the back of the house and one in basement. Can this be done? I will be using this basement at least 50% of the time. Will this be a problem? Currently there are 2 heat supply vents in basement. 1 in theater room and 1 in other section. The basement is normally proper temperature. On really cold winter days here in Canada in may be a little cool but only a few degree difference then the main level.

Thanks for all your help!

Sure it should work,, you didn`t say how big(what size ) the return is in the upstairs living area is,you might if possible make it larger so as more air can be pulled in from living area