On Sun, 10 Feb 2008 23:42:31 -0500, mc wrote:

"Donna Ohl, Grady Volunteer Coordinator" wrote in
message ...
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.

Strange. Then it isn't a measure of efficiency.

I think it was MY MISTAKE to call it an efficiency factor.
It's actually an ENERGY FACTOR.
And, it seems to be independent of the capacity of the tank.
It's dependent on the "cycles".

So, it seems if a 50-gallon water heater has an EF of 0.50, then it takes
two kilowatt hours of power to "cycle" that water heater. Likewise, if a
100-gallon water heater has the same EF, then it takes the same amount of
power to "cycle" that water heater.

Now we have to figure out what a "cycle" is.
I can presume it is to heat up a stated amount of hot water, presumably the
capacity but I don't know that for sure.

If a "cycle" is the capacity, then it would actually cost LESS per gallon
for a 100 gallon water heater than a 50 gallon water heater assuming the
same Energy Factor.

Realistically, all the Home Depot water heaters have a 0.58 or 0.59 EF so
that would indicate, if my assumptions are correct, they the larger ones
(e.g., 50 or 60 gallons capacity) actually costs LESS to operate than the
smaller ones (e.g., 40 gallons capacity) for any given number of gallons
USEAGE.

Can my math possibly hold water?