Originally Posted by nma
I am looking to replace an 80% efficient gas tank heater with either a gas tankless or a Marathon 50 gallon tank unit. At the moment I'm tempted to go for the electric tank unit.
We used our 1500 federal tax credit on a 2.3kw solar system last year, and so our electric bills are cheap and we can't claim more tax credits on the tankless - am I missing something?
The watts (BTUs/hr) into the tank affect the recovery rate.
With some fuss and conversion factors you can find the input BTUH for your gas heater and compare recovery times.
The heat loss for a tank water heater is about 50w, all the time, so 50w x 8760 hrs/yr = 440 kwh/yr.
For an elec. tank WH, knowing the heater element wattage, you can measure this heat loss with an analog elec. clock. Yes, you can!