Given your description of the heater on propane, my guess would be that the heater is set to NG. Your flame should be only 1.5 - 2 inches long, and be blue with a slight yellow tip.

Assuming a multiple burner set, you might check the tubes to ensure they are clear. But usually, if the tubes have anything in them, the flame would be small, and weak. Correct me if I'm wrong, but I'll bet the flame you had sounded loud. Roaring even. That tells me that the orifice was too large for the type of gas. Was the pilot flame also long and more yellow than blue, with a noticeable space between the flame and the tube? I'd bet it was.