I keep telling my husband that my large BGE can burn for 20 hours on one load of lump because that is what I have read on this forum. Mine has never lasted more than 15 hours, though. Last night I cleaned it out, put large pieces on the bottom grate and did everything I have read to make it last 20 hours but in 15 hours, I was empty. Any suggestions? I end up moving my butts to the oven to finish them every time. Could it be that my gasket is leaking? Thanks.