On Feb 1, 6:51 am, "Paul of Dayton"
wrote:
Hi Folks -

This one has me stumped. When we bought this house 5 years ago, we quickly
discovered it was easy to run out of hot water. I did the usual checks to
see if the WH was connected correctly and also checked each plumbing fixture
to see if a bad valve might be allowing the cold and hot to mix. I finally
chalked it up to on old 40gal gas heater full of gunk and turned the temp
up.

The heater finally died this summer so I replaced it with a 50gal unit with
a larger burner. I set it at the recommended setting and figured all would
be well. Lately, I find we are running out of hot water again. This
morning, one shower emptied it. It is burning correctly, just full of cold
water.

I bumped the temp up a bit but I really liked not burning my hands to a
cinder with hot water. There has to be something causing this but I am
stumped.

By the way, the old heater wasn't significantly heaver than the new one
after I emptied it.

Any ideas?

Thanks!

PoD

--

Never attribute to malice that which is adequately explained by stupidity.

-Hanlon's razor

I think the key is:

........Lately, I find we are running out of hot water again. This
morning, one shower emptied it. ...........

and

....... I set it at the recommended setting and figured all would be
well. .........

With a traditional tank style water heater there are couple of key
variables.

tank size, water heater recovery rate, water heater temperature
setting, hot water usage pattern & cold water feed temp

If the lack of hot water kinda went away last summer when you replaced
the old 40 with a 50 (does the new one have a better recovery rate?)
then I would guess that the problem came back because of a drop in
cold water feed temp in your area.

Plus mfr's suggest a "low" setting for energy savings & to avoid
liability wrt to scalding.

In my house the water heater is a small utility vault /
basement....access is via a small closet door & a stairway.....the
best I can do is a 40 but I made sure it had a better recovery rate
than average. It's in SoCal, so even in the winter the cold water is
usually about 60/65 at the coldest.

In colder areas of Ca (mountains) the cold water can get down to a
bone chilling 40/45F.....so cold that using cold water alone can be a
painful experience.

In addition as the cold water temp fails, one uses more hot water in a
shower situation........ in "normal" shower situtation closer to 1 to
1 mix will give you a decent shower temp. When your cold water temp
is COLD you wind up closer to a 2 to1 mix.


The solution most folks use is.....boost the water temp but that
increases the risk of scalding & increases energy loss to the
environment

The scald risk can be avoided with a tempering valve downstream of the
water heater.

As if there are not enough things to think about ........with
electric water heaters, there is a significant risk of Legionnaire's
disease bacteria being able to thrive at water temp setting of
120F...... even boosting to 140F doesn't eliminate the risk. Gas /
oil fired water heaters do not seem to have this problem.

cheers
Bob.