Well sounds like you guys are looking for some data:
- I used a draftrite pocket gauge to measure draft - no manometer
- The firebox measures 14" across 12" front to back and 4 1/2" deep
- It takes a bucket of coal about 25 lbs
- The fire bricks cover the edges so the grates take up the whole bottom
- Turns out the chimney is Duratech with a ceramic refractory 7 inch- is likely ok
- The interior pipe is double wall Selkirk dsp 6 inch
- I drilled a hole under the baro for the draft gauge - it's kept plugged with a bolt
- I have a magnetic flue thermometer under the baro as well
It sounds to me like you are doing everything correctly. Your fire is progressing as should be expected when you first light and fill. As I suspected, your firebox is small and shallow ( my Hitzer 30-95 firebox is 9" from the grates to the top of the firebricks). That seems to be a common drawback to stoves that are designed for wood or coal. It takes me an hour to get a coal fire lit and the coal burning to the top of the pile. Coal burns hot, but by no means gives off instant heat. This slow warm up and time consuming start up are two reasons most of the guys and gals on this forum attempt to keep thier fires burning for the entire heating season. Sometime when you can be home for 2 or 3 days, try keeping a fire going with the stove body temps about 400* and the stove pipe temp will probably be arround the 200* you have had. I think you will find that your stove will be reaching about all the output it has in it without pushing the operating temps beyond what you may want to do on a continuous basis. The real answer is that to heat a house, even a small one, and not have to stoke the fire every few hours, you will need a larger stove.
There are a few things you can do to extend the burn time of your fire. 1) Try pea size coal. 2) Fill the firebox to the bottom of the load door, then, if the firebricks are higher than that on the sides and back, "bank" the fire by adding additional coal up to the top of the bricks in the back, sloping down to the load door level at the front. If the bricks are not higher than the load door bottom you may try adding another course of bricks laid on their sides allong the back and sides of the firebox. If these suggestions for greater coal capacity are not practical for you, at least mound the coal up in the middle as much as you can.
Perhaps others will have additional ideas that will help you get the performance out of your stove that you would like. Best of luck.