On Sun, 10 Feb 2008 23:10:47 -0500, mc wrote:

Or does the 50 gallon water heater actually cost more
even if it's the same efficiency factor?

Heating less water costs less, even with equally efficient heaters.

Are you sure?

Look at what this energy page says about the Efficiency Factor:
http://www.friendlyplumber.com/plumb...er_energy.html

The "energy factor [is the] number of cycles that can be completed w/ one
kilowatt-hour of electricity".

If that's true, then it's independent of the VOLUME of the water heater.

So, if I read that correctly, a 40-gallon water heater with an EF of .58
takes roughly about 2 KWH of power to heat once while a 50-gallon water
heater with the same EF would take EXACTLY the same amount of power to heat
all 50 gallons.

Can someone check my math on that web page and report back if I understand
incorrectly? If we turn off our brains, of course 40 gallons would cost
less to heat than 50 gallons; but if we think, it might not be so.

Can you help me think about this properly?
What does the Efficiency Factor say about costs for two different sized
tanks with the same efficiency factor?

Donna