Completed installation of 5, 6†supply and 1, 30x6 return in the basement. Cut the supplies into the existing ductwork and piped them out to ceiling register boots. Put a double wide (30â€x6â€) low sidewall return on the common wall between finished and unfinished sides of the basement and then piped it to the return duct. Left the registers on site, John will call when ready for us to return to install the registers. Thank you for choosing Black-Haak Heating. Please take a moment to fill out our online survey.