Since I preheat my domestic hw with a home brew heat exchanger I wonder if I would be better off using an electric water heater. Presently I have a separate 50 gal tank that the cold water enters, when the wood boiler is running it makes hot water thru my heat exchanger. (5 ft of 2inch black iron pipe with 1/2 inch finned copper running thru it) and that feeds into my gas water heater. My nat gas bill varies from 5 to 17 therms per month. 17 therms is about 38 bucks. I was wondering if it would be better (cheaper) to use an electric water heater, since there would be no standby looses. When I googled a therms to kwh calculator it says 17 therms equals 498 kwh. Is that correct? IF it is gas is much cheaper in my area. Any thoughts.
Mike
Mike