I just got back from a freinds home in Sweedon Maine.He has just finished the install of his Vigas 40 (with lambda) and 2 500 gallon stacked tanks. He is heating a 2500 sq. foot home and domestic hot water.He added a small boiler room on to his home to house the tanks and boiler and ran the 1.25 copper through the basment to his existing oil boiler.Every things looks great,his plumber did a super neat install.WE lite the boiler and every thing worked as planned. He still needs to insulate the tanks this weekend,but we had the tanks climbing in temp nicely.He is very happy with the boiler and the install and looks forward to ending his monthly oil bill.