Great Lakes Cleaning Systems http://www.greatlakescleaningsystems.com Great Lakes Cleaning Systems - News en-us Time to Schedule A Furnace Cleaning http://www.greatlakescleaningsystems.com/rssnews.php?nid=Its-Time-to-Get-you-Furnace-Cle It is time to schedule a cleaning of your waste oil furnace. Due to a build up in ash over the heating season, waste oil furnace must be cleaned every 800-1000 running hours. Our cleaning includes romoval of the ash from the combustion chamber and f... Great Lakes Cleaning Systems 2008-08-28