My wife has reminded me we should have installed an on-demand LP genny, but we bought a Honda 7000IS inverter few years ago. Was pricey, but runs like a champ. In eco mode, I'm getting about 14hrs on ~4gal or about 0.29gal/hr. At $3.11/gal, that's costing us $0.90/hr. If we were using LP at an avg 1gal/hr, that would be $3.75 based on most recent tank fill. I know there are lots of benefits to on-demand, but I can't see spending 8-10K on such a unit for the convivence.