I don't feel a grate is the right thing to do. Personally, I had a coaling issue until I reduced the heat load on the house. When the house was drafty and lacked attic insulation, I was forced to keep a flame or get cold. Now with a tighter more insulated home, the fire can run in cycles. Whether smaller loads that put some heat into the home then peter out, or larger loads that last for hours. Three decent sized splits in a coalbed burn for quite some time. Above 25-30 degrees and a half load will take me thru the night with plenty of coals for the morning. Hell...Sometimes in the mid 20's to the 30's, I'll go down to check the fire and it's almost out. The blower hasn't ran in over a half hour and the house is still 73 degrees. With a tighter home, I don't stress about the next load. It was so bad before, when the blower would shutoff, I would scramble to get the woodburner, or the temperature would drop in the house.