My Ribbon burner Forge in Video and Multimedia Posted September 21, 2020 Hi TerryWay/Alan, I posted this is a different section but i'll post it here too for more visibility. i have a 1.5" coupling on the back, about 1.5" of inside plenum space about the refract, and then 21 crayon sized holes (5/16" D). My surface area math says that the inlet is equivalent to ~23 crayon holes so i figured by going down a couple of crayons, that will provide back pressure enough to keep the ribbon burning running. Is it possible to have too much backpressure? what would i see if so? I ran the forge for awhile the other day. my flame cones looked stable, weren't too greenish or spitting yellow flames and weren't wavy blue as if there was too much air. it ran real well for awhile but right around 2100 degrees, the flame blew back into the plenum. i shut the forge down, did something else, and then fired it up again. sure enough - ran well for an hour but when it started to get up to ~2100, it blew back again. I have no idea what the issue could be at this point. Any assistance would be well appreciated.