Jim-

I have an older home with "utility basement", the only W/H that fits
throught he door & down the stairs is a 30. Another home had the W/H in
a SMALL closet, the old 40 fit but the modern 30 was the biggest unit
thta fit w/o taking the clost face off.

SInce both homes are in SoCal cold water is rarely very cold.

The size of your water heater will be driven by:
inlet water temp
instantaneous demand

if you "demand spread" & your inlet water temp is not ice cold: a 30
will work just fine

If your inlet temp is COLD, you'll need more capacity


A high recovery rate W/H can nearly keep up with ~1gpm hot water
demand.

cheers
Bob
Jim Redelfs wrote:
I am going to replace my old, conventional gas furnace and gas water heater in
about two weeks. Now comes the part where I do my homework - studying I have
NEVER done (furnace) and only once, briefly, for a water heater.

My contractor has recommended that, now that our home is occupied only by me
and my wife, we downsize the gas water heater from its current 50-gallon
capacity to a forty.

Although our home has one full and two "3/4" baths, the shower in the finished
basement is virtually never used. We only occasionally have overnight guests
but, with three grown daughters (two with children), we VERY-occasionally
(rarely, really) have four adults and little kids for a few nights.

Obviously, I do not want to REGRET downsizing. The fifty-gallon gas water
heater I have now was a "spec" unit when I bought this home while half-built -
a spec house. The new one I am considering is called a "forty" but is rated
at 38-gallons with a "high recovery" rate of 48 atop a 50k burner.

Will this one do the trick for us, with a little PLANNING done when the kids
are here (VERY rare for overnight/shower/laundry use)? TIA!
--

JR