If a pressurized storage system is used, is a seperate dhw coil put into the storage tank? If the boiler is fired and the tank brought up to temp and then the boiler cools off would it not be inefficient to pump that hot water back to the boiler to heat the coil. In the case of a wood gun you would have to reheat the 80 gallon jacket and then that would disipated into the boiler room.