I have a portable air conditioning unit and I was wondering if it would be OK for me to set the exhaust tube down a return air vent because I don't want to set up my portable air condition at the window. Too many bugs get through if I leave the window open.

Use the window and block off the portion of the window that is not being used for the exhaust. I believe you will find this information in the book that came with the unit.

Heat rises and by trying to force the exhaust down a return air the heat will only come back in the area eventually.

In addition, if the unit isn't placed through a window you will likely have water puddling on the floor.

In addition, if the unit isn't placed through a window you will likely have water puddling on the floor.

I don't think he is talking about a window unit, but a portable unit.. But I could be wrong, sometimes you have to wonder. In any event the exust air should go outside. Like hvac said it will soon come back up so it would really not do any good to put it in the return.