My best friend Charlie had a late '60's VW microbus. We lived in New York at the time & anyone who has ever driven one of these through a northern winter knows how cold it can get inside, since the air cooled VW's had no heater fan. You had your choice of airflow, floor or windshield, and either cool or warm air. My friend came up with a great way to heat his van by installing a pot belly stove inside & cutting a hole in the roof for the smoke stack. The first time we took it out at night turned out to be the last also. We fired up the stove after leaving a party for the ride home. We got pulled over by the police who said we had red hot embers shooting out of the smoke stack for a quarter mile, and that was a big no-no. The police ordered the van off the road until Charlie removed the stove and patched the hole in the roof. That was the first & last time we had real heat in the VW Microbus.