1) try as i might i can't find a calculator that shows the cost comparison of operating a 99.5% efficient electric tankless h20 heater at .14$/kwh vs a 85% eff gas tankless heater at 1.825/ therm. Does anyone know where i can find an operation cost calculator or know what is cheaper to operate?
also, my contractor bid on installing a gas tankless unit but unilaterally decided to wire for electric. I know i can't ask install pricing questions so how can i find out how much money i should ask back for since i've read gas tankless units are more expensive to install then electric units.
2) I had manual J done on my house (a tiny eco home) came back 23K heat gain and 27K heat loss...but the unit they sized to match this is a 46K btu furnace--that 75% larger then the heat loss--is this standard?