I have a Crane 4 section cast iron boiler (made in the 40's to burn oil or coal) that I have been burning wood in it about 30 years. It's tied in to my oil fired boiler, so long as water in wood boiler is above low set point a circulator moves water between 2 boilers. Fire is controlled by a very old actuator that opens a draft door on bottom of boiler when water temp. drops. Actuator is not a spring return model that would close draft in case of power outage. Big trouble if fire box is loaded, draft is open and power goes out!! Draft control is always left on closed when not home and at night. When burning large chunks of wood recovery time is slow. I think installation of an induction fan to replace the draft door would greatly improve my recovery time and perhaps my wood usage. My concern about power outages would also be gone. I have to date only found 1 product that might be what i'm looking for but its quite expensive (Vogelzang Draft Kit $260). Does anyone know if this or a product similar to this closes off air supply to fire when the fan is not running. Wood used to be free and I used to be younger. Thanks Ray M.