Just a little background: We heat ~4k[\], of new construction, of which ~600 is an attached garage. All heat is pex radient. Prior to the first date on the graph, the residence was not finished above grade, so we heated the basement (~1200[\]) only, and that with a propane 40 gal DHW heater. At that time the DHW was provided with a second 40 gal tank. In Oct 2005 we installed a Viessmann Vitola 100, with a 50-gal Vitocell indirect. The X axis is scaled at 30-day intervals. The burner is a Riello 40 F5, .75 - 1.5 GPH. The graph will not tell you anything about usage before the GreenWood install because I was not recording prior to that point. If you get nothing else from the graph, laugh at the poor bass turd that used to sell me oil :lol: The second graph shows the difference between my first season with the GW and my second(incomplete). I think the best thing here is to see how much better the second year is going. I actually am running with the burner unplugged this year, though as you can see I had to fire it up a few times due to OE. And will need to for a few trips too. For any newbies that are frustrated with your units. . .hang in there. The learning curve is steep, but the payoff is suhhweeeet!