Ok, well this is my last ditch effort, does ANYONE on here know how to calculate duct sizing needed for a heater. I froze my ass off last year in my shop, I have a heater, but can't get any help in figuring out how to run ducts. The HVAC people in this town, are no shows, been waiting on one of them for over a year, and 8 months on the other one. NEED HELP, MY SHOP IS COLD!!!!!! So tired of this town………………………………