or can i get by without one?
A beer tap that looks like a fire hose.
Does the furnace use pvc (plastic pipe) or metal to vent if it's pvc it shouldn't be going into the chimney it goes out the side of house. If it's metal you my need a liner in chimney. Anytime you have a appliance that uses fossil fuel you should have at least 1C.O. detector in house. Had a family last week that was probably saved by one it went off at 3 A.M. woke them up. We found a crack in the heat exchange.
