I have 2 geothermal units I installed myself a yr ago, and I have a pellet stove. Been meaning to write up the geothermal installation in the projects section, but haven't gotten around to it. Actually I still have ductwork mods to make on the downstairs unit. This is my first winter running heat with geo. My upstairs unit was struggling a little when we had single digit temps, so I finally turned on the electric backup. I looked at my electric meter this morning, my next bill is going to be a little high, but I have saved a lot by not burning any oil this year (about $1000 saved). I still have my oil burner, but I think I will get rid of it, it's 15 yr old. I used around 700 gal/yr oil before I added the pellet stove, dropped to 400-500 gal/yr with my first non automatic pellet stove, and then put in a Harmon XXV automatic pellet stove and still used about 300 gal/yr after adding the pellet stove., this is a great stove The pellet stove is on my first level, so I normally don't run my first level heating unit very much, usually just the 2nd level.