So right now we have 2 heat runs into our bedroom which is 192sq ft. We want to expand a doorway downstairs but one of the registers is in the way that feeds our room. How many would remove the heat run to go forward with making the doorway bigger. It would make the doorway between our living room and dining room from 40in wide to 66 inches wide. We also have a wood burning fireplace in the livingroom so opening the doorway up would help get some of the heat backing more the house