On Sun, 23 Aug 2009 12:18:37 -0700 (PDT), stan
wrote:

On Aug 23, 4:01*pm, bob haller wrote:
On Aug 23, 1:00 pm, ransley wrote:

On Aug 23, 8:17 am, "desgnr" wrote:

Would there be much difference in operating costs for a 40 gallon gas water
heater vs. a 30 gallon ?

--
Dell Inspiron
Pentium dual-core 2.2 GHz
2 GB DDR2 SDRAM
Windows Vista Home Premium SP1

If I was shopping for a water heater I would go towww.energystar.gov
and compare all by EF, Energy Factor is their efficency rating.

far better off with the larger tank.

Vertex tanks are very high efficency and now qualify for the federal
30% tax credit. Plus their recovery is awesome. Never run out of hot
water

although vertex tanks do cost more.

Since our fairly well insulated (as from the factory) ELECTRIC hot
water tank, in our slightly cooler basement loses heat so slowly that
the water is still tepid after being away for a couple of weeks with
it completely shut off (Yes that surprised us too!); opinion here is
that heat loss from the tank itself or because a larger hot water tank/
heater be installed is almost insignificant.

After all;even a heater holding twice the amaount of hot water does
not have 'twice' the surface area from which to lose heat!

e.g. Volume for a 'round' tank = circular area times height!
and twice volume = say, twice circular area times same height.
Since area = pi x r squared; the r squared would only have to double
for the tank volume , or in other words the ' r ' (unsquared, would
only have to increase by 1.4 times. And consequently the outside heat
losing surface, of a tank holding twice the volume would only increase
1.4 times. So one could argue that, for that small difference, a
bigger tank might be more efficient: in not losing static heat?

What does cost the money is to actually heat the water, by some 100
degrees F from typical ground water temperature of say 50 deg. F to
perhaps 150 deg. F. Note 1. After that how much hot water is used or
wasted etc.?

Gas (except expensive bottled propane) not available here so have
never used gas hot water heater.
Understand the advantage is that piped-in gas is a relatively cheaper
fuel and/or the 'recovery rate of a gas powered hot water heater can
be faster? Whether that in itself leads to more usage depends on the
habits of the occupants/users.

Note 1: Some health departments call for, or recommend at least 160
deg. F for sanitary/safe dish washing! Whereas to prevent, say
children from scalding themselves nothing higher than 120 deg. F is
recommended!


Less then 120 degrees is a risk. They did this at the Ohio State
University (to reduce energy usage) and it made several thousand
students sick due to pathogen growth.