It would take major digging to find what little documentation I have. Somewhere between 60 and 80 gallons sticks in my mind.
Below is a section through the Burnham. There are 16 tubes 2 -3/8" diameter. There is an insulated top cover that unbolts for access down through the tubes. The baffle is actually 4 strips of 1/4" steel that slide out. They are a weak point, they burn out and droop. I think the original ones were some sort of high alloy plate. I just pick up new plates every few years from local steel fabricator and when they start drooping I remove them and bend them straight. The air flap is controlled by a temperature switch, if the boiler goes over a high setpoint it closes. Its either open or closed. The goal is never have the flap close during operation. The jacket temp probe controls the return water pump. Below 140 F the pump is off, once the jacket goes over 140 F the pump turns on. There is also an overheat probe that if the jacket water exceeds a high high setpoint the system goes to a dump zone. There is also two safety relief valves, one of them are routed to the firebox. It was set at 13 psi with the main safety set at 15 psi but the originally 13 psi one is leaking and finding an affordable one has not happened so I have a 15 psi one on it The bottom grate used to be rotary shaker that could be accessed with a hand crank from the ash pit. The shaker was trashed when I got it, I have some pieces but a friend welded up a grate out of square stock that dropped in. The clearance between the baffle and the loading door is tight so not a lot of room to put in heated secondaries and controlling the secondaries from outside the boiler would be difficult. my guess is burn it hot and fab and install a economizer in the upper cleanout space between the upper tube sheet and the flue connection.
I think when new it was shipped with refractory shipped separately. It has a sheetmetal case. When I got it, it was a illegal install necked down from 8" to a tee in a 6" oil boiler flue tied to fairly short outside stack. The front of the wood boiler was black with smole above the loading door. It did not have storage. My guess is that it used a lot of wood and probably smoked the place out. My friend bought the place from a bank after it was foreclosed, she could not get a mortgage unless she had it removed and was going to pay someone to remove it. I offered to remove it for free and remove all the extra piping from the heating system and replacing the oil boiler flue. I had a friend help me. We stripped the sheetmetal case and everything else we could off the boiler and then rigged it onto a truck then hauled it to my place and dropped it in through a bulkhead. The controls were real basic. I had a winter on my hands while my employer was bankrupt so I reassembled it and got it working with no storage using mostly salvaged fittings . I didnt use it much as it was a PITA to use as it either burned full bore or overheated so it needed to be watched constantly. A couple of years later I got an American Solar Technics 500 gallon storage tank and then spent a fewmonths rigging up a lot more advanced relay based control system that mostly automates the operation of the wood boilerand the backup oil boiler. It is also designed to "fail safe" on the oil boiler. If I turn off the wood boiler master power switch the oil boiler works just like it originally did including all the thermostats and circulators. As long as the storage tank is above 140 F the system locks out the oil burner. I could automate it more but that requires a PLC and I did not want one as PLCs are notorius that the software goes out of date. I have a GE Fanuc system in my collection that suffered that fate. Relays may be "dumb" and complex but a ladder diagram, a multimeter and a jumper lead is all you need to diagnose. Its been 10 to 12 years since assembled and the only issues have been operator error.
The major limitation is my radiators. I have Slant fin and they are undersized for low supply temps. If I had low temperature emitters I would have a lot more hours of storage but the cost would pay for a lot of cords of wood. Maybe on the next house but hard to spend more money when I get the wood for "free" and use around 3 to 4 cords per year to heat the house in northern NH. I have solar hot water free from April to October and in the winter I use surplus heat in the wood boiler after the storage is at maximum temperature to heat up a hot water maker via my oil system. I bring it up to 180 F and then mix it down so the tank lasts awhile. This feature is not well integrated into the controls but not that difficult to run.
