Same here, the BtU analysis always seems to askew ... usually with people later revealing that they live in Washington State with $0.04 electricity, people from the midwest with NG at half the price, or people not realizing that outside air temp has a MASSIVE effect on how much energy you use. My simple method: Last year $1700 to heat the house to 62 day/58 night during a modest year using NG. This year projecting $680 to heat the house to 73 day/70 night during what is looking to be a cold one. Looking to save roughly $1000-$1300/yr so it'll take a 3-4 years to pay for the stove, after that its all profit. X factor: NG is up 20% so this year it would have cost $2000 to freeze my ass. The bottom line is that the efficiency of my NG for my forced hot water system is unknown, the stove is unknown, the pellet BtUs can be all over the place. But here goes the open invitation for someone to parachute in and tell me how warm I would have been paying $2000 for NG this year. KEYSPAN employees and amateur physicists are especially welcome.