The more coal you can get into the stove, the longer the fire will last, but heat output is strictly governed by the amount of air you give the fire & the draft. Amount of coal loaded has no effect on heat output.
Would the air draft be the manner in which the stoves control btu output(ie. 5-70k btu option)? I thought they did it by controlling the amount of coal that automatically feed into the bed. By controlling the air draft is it safe to say that all coal stoves
can have their btu output controlled whether it's feed by hand, hopper or gravity?
I'm not HVAC engineer but my understanding has always been this: The heat your stove creates only has 2 places to go.....Up the chimney or radiated into the room.The amount of heat generated depends on how much fresh air is going through the coal bed, which is effected by stove air controls & the draft. The more open your air contols, the more air available to the fire.....BUT....if your draft is too strong you will lose heat up the chimney & burn through coal faster. Conversely, if your draft is to little, your fire could be starved for air & be weak or could even go out. A weak draft may also back up odors & possibly CO into the house, not give off much heat & be impossible to control. I suggest your read the threads on Barometric draft controls too.
If anyone has anything to add or correct...feel free...You wont hurt my feelings![/quote]
Nope.. that's about right, in theory.
However, the "actual" answer depends very much on the stove itself. Is it airtight, a-la a Harmon? Or is it some leaky old monster where half your air coming in is coming from cracks or gaps between the walls and lid of the stove?
That will all vary how much _real_ control you have with the bottom damper.
I just figured the deeper the coal bed the more _burning_ coal you have, so you have more collected BTU (3x the glowing coal should be somewhere near 3x the heat, right?) so, for instance, a 3 inch coal bed at full draft is not going to give you the same heat as a 12 inch coal bed at full draft, assuming the stove is well shaken, has a good draft, etc.