posted 1 month ago
Well, anecdotally speaking, I know a guy who has put bits of plastic in two different J-tubes. He always waits until they're up to operating temperature and rocketing along nicely, and then he'll drop in a few bits of plastic alongside the wood that's burning. He goes for a low ratio of plastic to wood, always keeps an eye on the exhaust for any visible smoke (none), and occasionally walks downwind to see if he can detect any "off" smells (again, none). He's done this with polyethylene, polystyrene, nylon, polyester, PET, milk jugs, sandwich bags, bale twine, and broken garden hose. The only thing that was ever left behind was fibreglass reinforcement that was embedded in a plastic coated tarp that was used as an outdoor billboard (great source of cheap tarps if you need to cover stuff).
This same guy also has a downdraft gasifier modification in his indoor wood fire, and has been known to throw the odd plastic bag or scrap in there when it's burning nice and hot. Either way, RMH or home fire, he's getting heat value out of a waste product.