I have not had any problems with ventilation. I have the engine exhaust and burner exhaust aiming outside with no obstructions and the engine drawing fresh air. I happened to be in the shop buying supplies and saw competitor of mine had a problem with his machine which happened to be the same exact machine as mine. The machine was placed to the front of the trailer the exhaust not aimed completely outside. The engine was drawing some of the exhaust back into itself. Needless to say it blew up the engine prematurely.