Epic69 where did you come by the Sequoyah? Company has been out of business for a number of years now.
A huge black box that barely made the original Phase 1 standard with a .56 emission output level.
8 hour btu output was low for its size and not very efficient for a gasser unit either. Saw one a number of years ago. If I remember correctly, it had a huge water jacket and very poorly insulated, with a huge blower fan for air input.
I think Matty is correct, the switch you are referring is probably just the main power switch. The aquastat called for heat so fan kicked on to blow air into that huge box. Fan should turn off once water has reached set point and it probably required a great deal of wood to bring all that water up to set point the first time. So yes the switch should be left on. I think the aquastat on it looked like what Pro Fab or P&M uses on their furnaces. I don't remember how the water temperature was displayed.