Question: I recently came across these terms regarding oil stoves: A vent and L vent. My search revealed nothing. Can you explain them? Answer: L-Vent is for Pellet Stoves and certain oil burners while a Class A chimney can server higher temp appliances like woodstoves, coalstoves, etc. (in addition to oil, gas or pellet.) Class A chimney can be a lined masonry chimney or a metal one, while class L is metal only.