Although we strongly recomment using the Vent-Sure downdraft vent there are some kilns that do not have them.
The molecules of air (which expand during the heating of the kiln) do not carry many BTUs. The hottest the air gets at the output of the motor is about 140°F.
It is fine to go through a roof with the L&L Vent-Sure kiln fumes vent system.
The Vent-Sure downdraft kiln vent is pulling not only air but moisture and the products of hot moinsture and the chemicals that are present in the clay.
Installation instructions for L&L's Vent-Sure Downdraft Kiln Vent.
See this page.
You need to vent fumes from the kiln and the room and heat from the room.
A customer asks if he can interlock his automatic kiln so that it will not fire unless his ventilation system is on. How do you accomplish this?