This is very similar to the simplest design but has all the water pass through the tank. The problem I found with the simplest design is that when the load was calling, no heat would transfer to the tank and on cold days, storage would not charge at all. With this design, the hot water flows into the tank and gets sucked right back to the load when the load is calling for heat. Now you do get some heat loss but its not near as bad as I thought it would be. If its a cold tank at the start of the burn, My load may see 130-140 deg water initially but it rises quickly as the tank heats up. If the load is not calling, then I get a full transfer of heat to storage just like the simplest design. The highest I can get storage on a cold day when there is always a call for heat on one zone or another is 170 deg at the top of the tank. My Econoburn 150 gasify's continusly until storage is charged using this design. What you you think?