> Reeeealy? How long would you like to sit in a room with a natural gas furnace whose exhaust is not vented outside? That could be used to any furnace. There a

> Reeeealy? How long would you like to sit in a room with a natural gas furnace whose exhaust is not vented outside? That could be used to any furnace. There are byproducts in burning anything, that need to be filtered lest they start displacing the oxygen in the room at a fatal rate. I wouldn't want to start a wood fire in my house unless the vent was open.