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
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
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
By the way, the old heater wasn't significantly heaver than the new one
after I emptied it.
Never attribute to malice that which is adequately explained by stupidity.
Very weird, unless of course, you are taking real long showers. With
2 water heaters, and one of them brand new, it would seem your idea of
the hot water somehow being cross connected with the cold is possible,
though it would seem unlikely.
I'd perform the following quick and easy test. Let the system sit
overnight. Then before any water is used, try opening just the cold
faucets one at a time, and let it flow for a min. Go check the hot
water pipe coming out of the WH a few feet from the unit. If it's
hot, you'll know that somehow the hot and cold are interconnected.
I'd also measure the temp of the water coming out of the hot faucet.
I think I have mine at about 130, which isn't real hot and I don't run
out here with a 40 gal unit.
I think the key is:
.......Lately, I find we are running out of hot water again. This
morning, one shower emptied it. ...........
...... I set it at the recommended setting and figured all would be
With a traditional tank style water heater there are couple of key
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
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
The scald risk can be avoided with a tempering valve downstream of the
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.
I can't find anything to substantiate the claim of electric vis a vis
gas being any different and in fact, the only real substantive place
that I saw it reported specifically states they cannot associate the
observed correlation w/ causation owing to confounding factors in the
study, not to mention it was a sample size of (3)...
"Although the Legionnaires' patients were more likely to have electric
than gas hot-water heaters, the finding was confounded with water
supply source -- that is, people with electric water heaters were also
more likely to have non-municipal water in their homes. Therefore, we
can't conclusively determine whether water heater type itself is
associated with Legionnaires' disease risk."
I also found a brief quote from a report that indicates apparently a
followup study did not find any statistical correlation on the
electric water heater correlation. Here's a link and the blurb, but
am not IEEE member so couldn't read whole thing on line. DA(very)QGS
but didn't find the paper for further details.
"[h]ome electric water heaters were found not to be a. major risk
factor for Legionnaires' disease in a 2-year. study conducted recently
in Ohio. ..."
And, OSHA specifically notes while possible to acquire LBD from
inhaled mist in residential water systems, indications are the
probabilities are much less than for commercial systems and more
likely associated in the home w/ things such as whirlpools, etc.
"Q. Can my home water heater also be a source of LDB contamination?
A. Yes, but evidence indicates that smaller water systems such as
those used in homes are not as likely to be infected with LDB as
larger systems in workplaces and public buildings."
So, I think you can stop worrying much over this one...
What I found does indicate that it pays to take care when doing
maintenance on plumbing systems and especially if on non-municipal
systems to be careful of general contamination issues in potable water
supplies. That, of course, is true for a myriad of other issues most
of which are more likely than LBD imo (coliform, etc., come to
here's the report I ran across
I should have posted with my earlier reply & I cannot vouch for the
reliability of the report but it looked like it came from a refereed
btw I don't worry about LBD or scalding there are too many more
important things closer to the top of that list
The other issue is what type of shower nozzle you have? Low flow ones
provide less water but longer showers.
I would install a tempering valve, set the tank HOT thje tempering
valve at the temp you prefer.
cold winter water temp is likely the source of the problem
how many BTUs is the new tank? 75,000 is prefered, many are 35,000
BTUs:( or less
the tempering valve effectively gives you more hot water and will fix
The shower nozzle is certainly something to consider. We had an old
shower nozzle that would really pump the water out. It was great, but
the hot water would start running out towards the end of the shower.
No problems with a new nozzle.
That was my thought, your dip tube could be busted.
The fill for the WH is on the top, but so is the exit, so, to prevent the
cold water coming in from going straight out without being heated, there is
supposed to be a dip tube that brings the cold all the way to the bottom of
so, if you looked at your hot water heaters cross section, the bottom would
be cold and the top hot.
there was a class action suit a while ago where almost every water heater in
production had faulty dip tubes that would disintegrate after a few years
leaving the tank without a tube, I had plastic chunks coming out of my hot
tap for a while till the tub was replaced. The old tube was only 3 inches
long instead of the 3 feet it should have been.
since you say you have a new tank, its less likely that this is the case,
but is it possible the tube is cracked or not attached correctly?
IT's called a dip tube and it sounds like it was either never installed or
recently broke free inside the tank (but that's unlikely on a new heater).
Low-flow shower heads will certainly help. I have one with a slider "bar"
in the head that blocks off the flow of water so you can take a "navy
shower". I rarely use that as I take what sailors call a "hollywood" shower.
My shower head has one to those sliders. I use it often. I like to
turn the water off so I can apply soap without it getting washed away
I recently replaced a washer in the hot-water shower faucet. Now,
every few days there's a big pressure drop and I have to clean the
shower head because one or more pieces of that old broken washer got
stuck in there (right behind the metal disk with holes in it).
3 things come to mind: Is there a tempering valve in your plumbing system?
Is it possible that there is a dripping hot water faucet or maybe some kind
of appliance valve (washer, dishwasher?) and, what kind of showerhead does
your shower have? Have you tried a limited-flow showerhead?
Make it as simple as possible, but no simpler.
Larry Wasserman - Baltimore Maryland - lwasserm(a)sdf.lonestar.org
Thanks to everyone who answered. I have checked pipes and hot/cold where it
isn't supposed to be. I think the sudden cold snap here in Ohio is the
cause of my problem. As I mentioned in the 1st post, I have raised the temp
a bit. It made a very noticeable change at the tap. I'll let everyone know
if I still run out.
I live in Ohio as well, and I had the same problem with my house when
I first moved in. The wife liked to take Hollywood showers which
depleted the hot water tank.
My fix was installing a high efficiency shower head. We tried a 2GPM
shower head, but that frustrated the wife. I agreed with her as well
- there simply was too little water coming out. So I set off to Home
Depot and bought the 2.5GPM shower head. She reluctantly accepted
that shower head and got used to it real quickly. Now we can take
back to back showers without depleting our old 40 gallon tank.
Heat recovery is another factor. Hot water tanks vary in how quickly
they recover. Older tanks may have a large amount of sediment in them
which can reduce the amount of capacity. Flushing the tank once a
year normally resolves this problem.
Best of luck!!!
There is a company that manufactures shower heads compliant with government
The device consists of FOUR shower heads, each delivering no more than the
Big Brother mandated 2 gallons per minute.
Thanks for all the ideas, folks. The shower valve and head are quite new
American Standard antique look-alikes. I raised the heater temp a notch
which made a noticable change at the faucet. Didn't run out yesterday. I
figure the sudden cold snap was the culprit.
I appreciate all the help!
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