Hmmm...

What wattage do you use Connie? The one I am looking at can do 700, 800 or both together for 1500. Just crunching the numbers...1500 watts x just under 8 cents per kwh is about 65 bucks a month to run it 24/7.

The only thing I can think of to disprove this is the actual mechanism that the oil heaters use...full power for a while, then keep it constant using a lot less power?

Also, is the ranco really necessary to keep the temps constant or would tweaking the on-board controls be doable?