In article , "Donna Ohl, Grady Volunteer Coordinator" wrote:
On Sun, 10 Feb 2008 22:32:43 -0500, Nate Nagel wrote:
Hi Nate and others,
I appreciate the help.
One thing that confuses me to no end is this EFFICIENCY thing.

If both a 50 gallon and 40 gallon water heater has the same 59 percent
efficiency factor ... do they cost the SAME to heat?

Nope.

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

Yup.

The reason I ask is I assumed they cost the same to operate but someone
said the smaller water heater will cost less to operate even if the
efficiency factor is the same.

The smaller heater will be cheaper to run -- but it may not
provide enough hot water when you need it.

But the difference (between 40 and 50 gal) isn't going to be
that great provided the heater has good insulation.

The energy factor tells you how well much of the gas is
converted into hot water. A low rating on a gas heater
means lots of therms (energy) are going up the flue.

Can someone who understands this clarify if a larger heater truly costs
more to operate than a smaller volume heater even if the efficiency factor
is the same?

If your current heater is 40gal and meets your demands, I
see absolutely no reason to upgrade to a 50gal tank.

I'm in Northern CA and a 50 gal tank is just about adequate
for my home -- with 2500 sq ft, two adults and three kids.
We run a little low on hot water if everyone takes a shower
or bath in really quick succession while doing laundry.
It's a very minor problem about once a year. 99% of the
time, 50 gals is just fine.


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