Ian
barts wrote:On Rainbow, her Scotch boiler has a central firebox 13" inside diameter (the boiler is 24" in diameter). Being able to easily place firewood (16" x 2-3" x ~2-3") in the firebox is critical as the firebox is ~34" long and I'm often using the fresh firewood to shove the already burning pieces into the rear of the firebox. The door is often open for a bit as I load several pieces into the boiler at once, but this boiler reacts very slowly as it holds many gallons of water.
Our Otter has a Lune Valley style boiler I built that is oil fired. It responds quite rapidly to firing changes; if yours is similar you'll be likely working with smaller quantities of wood to keep more even steam conditions. Making it easy to spread the fire out will be important as well. You might consider having a stack damper (like an carburetor choke) above the boiler so that you can reduce the amount of cold air that rushes in when you open the firebox door; this could also be done w/ a lever & spring setup so that the damper closed automatically most of the way when the door was opened.
- Bart