I finally bought an Englander 28-3500 add-on which has been discussed on here from time to time as it is listed as a wood AND coal unit (not a wood OR coal). I spoke with a rep at Englander who basically said that they recommend adding about 10 lbs of soft coal to an existing fire once the wood is through the initial char stage which gives a couple hours to the end of the burn cycle. Just wondering what the best way to do this is. The furnace does have an underfire air control so that's not a problem, but how should the coal be added to the fire? Can it just be shoveled in or does it have to be placed specifically so as not to cause a buildup of volatiles? I was going to build a coal bin outside which will only hold about 2 tons and then periodically shoveling the coal 10 lbs at a time into paper grocery bags so that the bag could just be placed in the firebox. This way I could have a bunch of bags at the ready in the basement that the wife or I can throw in as needed. Does that sound like it will work?