I took some pictures of my home made boiler up and running today. You can only see steam escaping from the stack, no visible smoke. Also, I took a picture of the fire burning and the exhaust temperature after the 4th pass out of 5 of the heat exchanger. So far I'm very pleased with the performance. I generally get 20 degrees water temperature rise per hour when firing hard. My boiler is 3000 gallons (well maybe 2900 gallons removing the firebox and piping). when you add the startup time and the end of the fire when there is just coals, my overall water temp rise is more like 15 degrees per hour. Right now I'm relighting fire anywhere between 36 and 48 hours. If I get the water temperature in the boiler to approximately 200 degrees, I can still heat the house and DHW with water temperatures down to 135 degrees. The outside temperatures has been in the teens during the day and hovering between 0 to 10 F during the nights and I have been able to go 48 hours between start to start of fire (started a fire Saturday at 16:00 raised water to 200 degrees and let fire go out by 22:00 Sat, relight today (Monday) at 15:40 last small load of logs by 19:30 and fire will be out by 21:30-22:00. I figure I'm using less then half a face cord (20-inches wide x 48-inches high x 96-inches long). I have been burning for about 6 weeks now and operating the boiler is extremely easy. I really think that the more water storage the better. I really like only having to worry about the fire every second day.