I have a quick plumbing question. I just bought an old house with
a very new 40 gallon gas water heater (mfg 2006). The hot water seems
very abundant at all the faucets. However, after running a hot shower
for approximately 4 or 5 minutes, the water gradually gets cooler and
cooler. Eventually, it gets uncomfortable and I can tap the knob (its
a single knob for temperature control) slightly warmer and it suddenly
is pretty much right back up to temperature for a short period of
time. After getting out of the shower, the hot water coming out of the
faucet at the sink is very warm but certainly not as hot as it usually
gets. I replaced the shower value with a new pressure balancing Kohler
unit, but it exhibits the same problem. So two valves are doing the
same thing. I did some research and though that it might be a dip tube
problem in the water heater. But I'm not so sure since I CAN get the
shower back up to temp at least for a minute or so and its a new
heater. Its seems very mysterious to me and I would appreciate any
help you can provide. Thanks in advance.
I'd think that it is still the dip tube, that still makes sense even though
you are getting the temp back up for a minute. When you initially turn on
the tap, the water temp you feel is being cooled by the cold that is
included in the stream. if you adjust the knob it only makes sense that
with less cold now running, the water would feel warmer. Do you have any
faucets with separate controls for hot and cold?
try the test on those, run the hot only wide open for a while and see what
Yeah, the faucet at the sink next to the shower has separate hot and
cold valves. With the hot valve wide open it still only gets very
warm, but not hot after a shower. That does make sense though, the
cool water flowing to the top of the water heater takes the hot water
output temp down quite a bit. By turning the shower hotter and hotter
we're just mixing in less cold water. But one interesting point here
is that by the end of the shower, no hot water in that bathroom is
ever as hot as it is in the beginning. So I suppose i'll investigate
the dip tube a bit more. Thank you for your help, Dave.
All modern shower valves had a safety built in to keep from scalding the
bather. It sounds like yours needs replacement, repair or adjustment.
The instructions are specific for different kinds and it requires some
disassembly. If you can fully identify the valve, someone might have the
instructions. You might want to google the valve type and maybe you can
identify it and find instructions. You can also check with the library or
hardware store for a book that includes some general instructions on this
along with some very helpful photos.
You are right. When I installed the new shower valve, I did not
adjust the temperature safely limiter. I was under the assumption that
after taking a temp reading at its "full hot" setting and it was at a
safe level it was safe and I just left it alone. So if this is faulty
or malfunctioning that might cause the temperature to deviate
substantially from its initial temperature? I hope so, cause I can
easily adjust that. Thanks.
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