Completed installation of a 6†supply to the living room of the house. Tapped a 6†start collar into the existing furnace plenum and ran a pipe to the side wall above the water heater. Installed a 4â€x12†register boot high on the wall of the living room and connected it to the 6†pipe. Thank you for choosing Black-Haak Heating and Electric. Please take a moment to fill out our online survey.