Gas is only used for the building’s generator, and the penthouse fireplace. For this page, I will focus on the fireplace. The great room on the M floor will have a chimney that I would hope will be able to exhaust the smoke and carbon monoxide out of a short stack chimney to eliminate the need to run the chimney stack to go through the U floor. The fireplace is not a necessity, but instead for a mood that may be desired. The underfloor radiant heating will support the heating needs of the penthouse.