temp just kept climbing all night

fishlessman

i stabilized a butt cook last night at 6 at 225 degrees dome. at 12 was at 225 degrees dome, at 2 the alarm went off at 260 dome,closed both damper a little, at 4, the dome was up to 275. closed the dampers some more. at 5:30 the dome was 300.wrapped in foil and leveled out the lump. the center of the lump burnt straight down making the air flow easier thru the lump. ive had this happen when its cold out but never in the summer.butts are almost done and i dont think that the climbing temps will effect them. any idea why the center burn out

Clay Q

fishlessman,
I'm no scientist but I have a theory. Colder air in winter fuels the fire, is heated and exits the dome with greater force than warm summer air. The higher contrast in air temp in relation to entering the bottom draft door and exiting the top is the reason for a hotter burn. More air is being drawn in by convection forces. Also, colder air is more dense with hydrogen and oxygen.[p]I hope your cook turns out ok.
Clay