I have a efel wood/coal stove. I want to burn coal in it.The air intake is in the back at the bottom of the stove.It doesn't really matter where i have the exhaust dampner at closed, fully open or anywhere inbetween.With the air intake set to max i can reach a surfce temp of 400 to 550 at the stove.If i close the air intake and open the ash pan door and the exhaust dampner fully closed i can reach around 720 to 780 degrees surface temp. Which is what i'm gonna need if i'm not gonna freeze this year... I have the stove located in the basement. I need to heat 2 floors.I have vents in the floors for heat to move around.The stove is solid cast iron 1/4" thick.The previous owners of this stove think it was rated at around 130K btu when using coal so that should more then enough to heat my house.According to another site my basement can support up to 176K btu stove. So will hurt running the stove this way for max temp?? Also i did check and there is no restrictions in the air intake side of the stove.It also vents into a 40' ss liner..I thought i was having a draft issue before but i don't think so.It seems more like a air supply problem