This is, by far the most informative & active forum I've ever seen. I have gotten some great ideas & plans here, and I've been bitten by the woodgas bug. I just bought a used Orlan 40 on ebay, and it's coming this week. I am building a 1000 gallon non-pressurized storage tank from plans I found on this forum. I'm installing a 40 tube solar collector on the roof, which will feed an 80 gallon Earthsun storage tank for DHW. I will install both DHW & BBH heat exchangers in the storage tank. Once again, I found excellent plumbing schemes here on the forum. My questions are these: Is it better to have a heat exhanger in the storage tank for a closed loop to the boiler, or is it better to have an open system that flows in one end & draws from the other? I will have a boiler protection valve, of course. I want to provide baseboard heat for one zone for the shoulder seasons when the sun isn't shining & I don't want to fire the boiler. I can buy a new Rheem 65 gallon electric water heater for a whopping $250 from a freight liquidator near me & use it to provide one zone of baseboard heat for these few days a year. Is this a good idea? I can also install a sidearm heat exchanger off this unit to preheat the boiler intake for maximum efficiency. Good idea or not? My intent is to completely remove my #2 heating oil boiler & use my oil tank to supply my backup generator, eventually filling it with off road diesel. I appreciate any responses, or anyone who has a similar situation, and especially anyone in southwest ct, who is active in this forum.