The burner system has been operated for about ten hours and exceeds expectations. The use of dual burners was new and a bit of experimentation was required to find a suitable operating process.
The best way to start up seems to be to light only one burner. A propane torch flame through the hole around one of the burners is one way to light the fire. The one burner runs very similar to the single burner in the Shay:
Once one burner is operating, the second burner can be turned on. The second burner has an identical proper operating fuel level. Too much fuel will cause the burner to smoke. However, the second burner can be turned down to any level --- the other burner that is stable will keep relighting the second burner if it goes out.
The two burners permit an adjustment from maybe 40% of maximum output with one burner to the maximum with the two burners.
When pulling a heavy load the fire will be less stable because of the added draft. Increasing the fuel slightly stabilizes the fire. The fire can also be stabilized by opening the damper in the firebox door.
I've had several discussions with Randy Sutherland who has run an oil burning Mikado for many years. This operation matches his view that each burner has a maximum output before it will smoke. The fire box volume will also limit the amount of fuel that can be consumed effectively. Apparently the Heisler firebox is big enough for two burners. At this point it's unknown whether the maximum is two or if three or four burners could be used.
I was skeptical as to the value of the refractory cement inside the fire pan. However, I now think it is a good idea. Any fuel that is not combusted drops onto the cement where it seems to evaporate and then combust rather than leak out as it does on the Shay which doesn't use the cement coating.
The two burners appear to provide sufficient steam even on the steep grades of Mill Creek Central Railroad. For the first few runs the second burner was turned on only when going up a grade; the single burner provides adequate steam on the flat stretches. More experience pulling a string of cars or a half dozen riders is required to provide a complete evaluation. I'll come back and update this page after some operation with greater loads.