After much help from Rudy it seems my AH was not getting enough fresh air. It always smoked at 8,000 ft. when starting up. Just finished doing a service on it after about 45 days of use half in summer and half in winter. Found the same gunk in the combustion chamber that was in the last service I did after purchasing it. If you do your own servicing be sure to pull out the combustion chamber and clean the inside of it. This is what was in mine.