Hey Glort, I own 2 of these heaters from China, one is in my 1974 vw bus Westphalia, the other heats my backyard mancave (12 by12 1.5 story building), the one in the bus runs about 30 hours a year (winter camping), the one in my man cave runs about 3 hours a night, every night in the winter.I have had 2 failures, the first was the cheapo thermostats that come with them, once I switched over to the simple one knob thermostats, that problem disappeared, the other problem was with carbon. You must turn them to full blast 15 minutes before turning them off, otherwise carbon will build up over time causing smokey exhaust and eventual no start situation there is no spark plugs in these heaters  only a single glow plug that operates at start up, once the combustion chamber comes up to temp, the combustion becomes self sustaining.No fears of exhaust gas leaking into the room air. The way they are constructed and the extremely small amount of fuel precludes that assumption.Feel free to PM me if you have any questions or need advice on installation or operation.

Interesting, the cutaway shows a fully counter weighted  crankshaft.