Trust me it's not 100 btus it's 50 btus. You need a 7200 btus. But whY the fuck do I know! Grape says 100 btus per sq ft. That would mean a little 1000 sq ft home would need a 100,000 btus. Never roughly 70,000 furnace for a 1000-1200 sq ft home. Other factors but this isn't hvac class