A couple of my buses still have those heaters installed underneath but disabled by previous owners. I've always been worried about trying to fire one up (in case way more than the heater fires up). When I was 16, I had an early 1970s squareback when I lived in Ontario. I drove mine year round as well. Since the heat came from the engine in the back and up to the front via the rocker panels, they had long since rusted out from Ontario-salted roads. The only heat I had was from the gas heater inside the front hood area. That thing scared me to death every time I turned it on (and in 25 below mornings, I had no choice) as it never ever seemed to be quite "right". As a teenager with limited funds from my various part time jobs, it seemed I spent an inordinate amount of it on getting that heater worked on many times in the local VW shop, "Red's Garage" in Petawawa. Near the end of that car's life, each day I turned that heater on, it blew black smoke (and I mean a LOT of black smoke) right into the car until it got going hot and then it was fine. My first 2 - 3 minutes in the morning heading into college (or my weekend job at the brick yard) I drove with the windows all rolled down so I could see through the smoke. Seriously. I dont even know how smoke could have gotten in as I imagine it's not blowing pure burned fumes in but I swear that's what it did. That car was always an adventure. d
For fun, i'm attaching the only picture I have of that car taken around 1977/78. The original photo had degraded a lot before technology came along and I finally scanned it into my computer some years ago. The racing stripes? Applied by me with a brush and can of gloss black rust paint. If you can make it out, I had white fur on all the surfaces inside, including the dash which made the controls quite the trick to use. That was the era of the Chevy Vans being made into rolling love machines and my little VW was not going to miss out. Yep. It was something else. Hey, I was 16.