Ted, lots of different setups out there. Mine is pretty simple. Stainless steel tank in a tank design. There are tubes inside the fire chamber that allow water to circulate as it heats. Mine holds approx. 500 gallons of soft water so I have a lot of heat storage. During the summer I only heat my domestic ( shower, tap water) water so I only put scraps in it every couple or 3 days. Only put enough in it to keep a few coals in there, doesn't take much to heat it. During the winter we put 4 -8 pieces of 6'X 32" long ash in it, maybe twice per day. We heat 2 houses, 2 domestic hot water and supplement heat a 25x 60 shop. I burn poplar and other crap during shoulder seasons.
The boiler has it's own aquastat and all it does is maintain what ever temperature I set it to. Insulated water lines run to the house and back to the boiler. My circulation pump is in the basement and runs 24/7. In the house there is a thermosat that is connected to my furnace and when it calls for heat it turns the fan on in the furnace exchanger.