Question: We built our house about 3 years ago and did not finish the basement at that time. We are now in the process of finishing the basement. We're gathering information for an alternate heat source (we currently have central heat and air) and have considered using propane to heat the basement. We are unclear whether we should/can use a direct vent or a natural vent. Can you help us???!! Our basement is completely under ground without windows or doors. We have asked this question of several "gas people", but we're receiving conflicting advice. Also, is there a length limit for the pipe to be with either vent system? With a direct vent, can you make a 90 degree bend of the pipe or must it go straight (horizontal) out the back of the unit? Answer: A direct vent might suit you better for a few reason. First, all b-vents must terminate at a point higher than the roof line. This means your pipe must go up one or two stories. Also, the B-Vent need combustion air from the room, while the DV takes it's air from outside. Each DV stove is different, but most can have either one or two 90 degree turns. There is also a device called a "snorkel" which can be placed on the outside of the home and brings the vent high enough above ground level to meet code...ask your dealer. There are limits to the length of most DV piping systems, but they are usually 25 to 45 feet, so this should not get in the way.