OMG, now King Cecrops (otherwise known as Pierre, although that king was part human and part snake and that is not a good analogy) joins in now we have three Greek Gods of coal burning working the issue.
. However, down in the sub basement of the Kings Palace worked a lowly janitor (let's call him CN) on an ACTUAL Invader stove. He used to give opinions but nobody listened to him.
Firstly.the issue of the btu output table. The stove has over 20+ sq ft of radiating surface and so if the stove was at 200* then the output equals that of a couple of electric fires (to a good approximation)
315btu * 20 = 6000 btu and an electric fire is about 4000 btu on a good day
If the stove was over 600* then it would be about 3000btu * 20 = 60,000btu
.... a big difference. If this stove is working right, think nuclear reactor. One of the best foundries in the world did not produce c rap.
Now as to the other issues discussed. Look at the brightness of the coals the fire is working fine - where it is working. There is draft aplenty the issue is surface area of burn and this is how I think the story goes. The clue is in that last photo. The fire is ashing up and only a small (and central) part of the coal bed is alight. You add charcoal to start and when hot add the coal. Good move as that is now I start my new Hitzer and it's an idiot proof way to go. Once alight you shake out the high ash from the charcoal bed and away we go and there is the rub you can't really shake out the ashes properly on this crippled stove and you only have a tiny fire in the middle. I think somebody said it was a crippled stove and that is the best you can do.... Gotta go, the speaking tube is whistling, the King wants more heat and I need to shovel. Let the fight over Athens continue... HAHAHAHAHAAHA, I slay myself, I am just sooooo funny.