The stove has two "ports"/little doors in its construction design , wich I gave up on and just added 2 chamotte bricks wich have a "ditch"/channel on 3 sides for a stainless steel wire bend to the shape of the brick wich can be removed for this purpose: to clean those places were ash/creosete might stick around!
I haven't tried yet to burn coal because coal its a high power fuel but I can get anthracite for about 30 cents us dollar 2 pounds(or 1 kg).
I have talked with one user here and it seems that this coal comes FROM YOUR COUNTRY...
But never mind that...
It should burn coal well because the air comes through a cast iron grate from UNDER the fire!
Even with wood briquettes or very dried wood it burns with a blueish flame when it's almost finished but this happens ONLY if the wood is over the grate through wich air comes in!
I was thinking about adding secondary air for better combustion but since this is my first masonry stove ,I chose to leave it as is!
This stove could be improved and turned into a central heating unit by adding a heat exchanger in the secondary "chamber" before the fumes go out the chimney!
As a note: the temperature on the stack doesn't goes over 90 degrees celcius no matter what I burn or how open the primary air is!
Maybe it's because the stove has lots of water in it wich "steals the heat" away...
But I'm working on that , by giving it a good fire every morning wich lasts/keeps the stove hot/warm for about 9 hours!
I hope it stays warm for a longer time but that remains to be seen when no water will be present anywhere in it!
I'm glad you liked the stove!