The system is auto-battery/inverter backed up for at least 35 hour of continuous power outage. The model is an Englander 30-NC with a 3.5 Cubic feet fire box which gets packed full of maple. Yes I can walk away feeling secure & I never adjust the manual stove's damper. The stove pipe sensor is a fix 300 Deg F thermal snap disc. and positioned 40 inches from the stove collar. At a later date I will be adding another identical snap disc in series with the 1st one; they are not expensive. (I'll call this alarm #1). My Fan Control accuracy reads the surface temperature of the stove and has it's own adjustable alarm setting . (alarm #2). I have an electronic digital thermostat with adjustable setpoint (I'll call this alarm #3). Any alarm will cause the damper to close. Flawlessly up to know. As per run-aways/mild over-fire I get one lets say every 20-25 loads.
Although my setup manages over-fires, it also regulated the temperature via the digital thermostat set point.
There are possible scenarios where the fire might die out in spite of secondary air, like If some of the wood was less seasoned or got damp in the stacks, and if the draft was weakened. The concern with the OAK in a basement is a draft reversal where the outside air duct becomes a chimney. This is a potential issue with a basement stove due to negative room pressure. Even if the basement is neutral with everything in the house off, it can go negative with the opening of a second-floor window, or turning on a kitchen exhaust fan while the dryer is running. This is why the OAK intake should be at or below the firebox floor level. In a basement install, a workaround is for there to be an air gap between the outside air supply and the stove air intake connection. Some stove OAK connections have this air gap built-in. Documentation for the 30-NC only includes a section for the manufactured home requirement, not the installation instructions for the OAK.
Great question. I thought of setting proportional positioning for the damper for the Digital Thermostat but I found no big advantage and the hysteresis is short. In one year I have never seen the fire go completely out with the main damper closed and I have spent numerous hours taking readings and observations noting trends. My burn time is about 6-7 hours of noticeable heat. The damper control via the Digital Thermostat basically act like a gradual proportion modulator. To answer your question the manual damper rest at about 85% open. I recorded so much data to learn the manual positioner, status at the start of the fire as well as temperature curves per burn for numerous similar loads. I had a ruler attached to the damper handle. "I finally got a handle on it". Please note that the automated damper doesn't close often and when it does it seem to be around 25 minutes after the new load, repeatable heat peak there. A closed damper for 3-4 minutes seem to make the fire box behave from that point on. I have seen it close a second time. Every load is a max full load for me.
Good point. I understand. Possible scenarios are endless. I must be lucky, because my draft is right on and I have not seen any back pressure issues. My 16 feet air duct run commences on the windward side of the house. Also the window air wash and secondary tubes get fed separately from below the stove/fire box.
