I purchased a used 20,000 BTU propane space heater for my single car garage/workshop. It came with pipes but I wonder if it "really" needs (I'm not looking for a fire or carbon monoxide poisoning)to be vented outside. The garage is far from airtight and the heater will only be used occasionally.

Only use the vent pipe if you don`t want to kill yourself,without venting,get extra insurance to support the family after you`re gone