Currently I pay approximately $2,000 a year for Natural gas. I use gas for my 14-year old, probably 80% efficient, furnace, gas dryer, water heater and stove. I got a ball park estimate of at least $30,000 for a geothermal system with a desuperheater. I would guess I might save $800 a year with a geothermal system, so even with the tax credit, I am looking at over 20 years for payback. Could this be right? I don't currently have air conditioning, so that would be an added plus. Am I missing something?