DIYbanter - View Single Post - Electric Water Heater Tripped for No Reason

wrote:
On Thu, 16 Dec 2004 10:19:12 -0500, Jeff Wisnia
wrote:

The "most likely" cause of it tripping is that either the upper or lower
thermostat got "sticky" and didn't open, and the temperature in the
heater rose to the point where the thermal overload tripped. I've never
seen one "trip by itself" with water in the normal temperature
range.(I'm assuming that since you mentioned opening the "upper panel",
there's a lower one too, so there's two thermostats on your water heater.

I would tend to disagree that the heater overheated. The OP said the
water was cold in the shower in the morning. If the water was
overheated, it would still be hot, or fairly warm. I can shut off the
power to my water heater and 24 hours later still have relatively hot
water (assuming someone did not drain the tank).

Since the OP has a well, I'd check the elements. Only 3 year old tank
does not mean anything in a rural area. Sure, the tank itself should
be in good shape. BUT........

Lightning can be nasty in rural areas because of the long runs of
overhead wires and few ground points along the way. A lightning
strike last summer may have blown a tiny pin hole in one of the
elements and discharged into the water. I have fixed several of
these, and its more common that you would believe.

You could also have a high acidic water that ate a hole in an element.

You could have a combination of both of these that finally drew enough
current to go POP.

It wasn't a CURRENT overload that popped.

Pull the elements and thoroughly inspect them. Wipe them down with
one of those green pot scrubbers (scotch pad), and you should see any
pin holes or cracks. Usually they stay wet after you dry the rest of
the element.

If thats too much effort, either learn to live with the hot water
cutting off more and more in the future, or hope and pray that that
someone broke into your home while you were away, and did it just to
trip that red button. By the way, if your income is at or near any of
those political idiots in DC, just buy a new water heater and donate
the old one to charity so some needy person can fix it.

21deg.... Geeshhhhhh, I hope the shrub freezes, shrivels, and wilts
away !!!!

Mark

I won't disagree that the elements could *also* be bad, but "how the F"
will that trip a thermal breaker?

If you've ever taken a thermal breaker apart you know that it consists
of a disk of bimetal formed into a shallow "dish". When the tank shell
reaches the "overtemperature" point the dish inverts (with a snap) and
opens a set of contacts which break the line voltage feeding everything
else in the water heater.

Now, tell us how a damaged element will cause the water to heat up
enough to pop the thermal overload? And even if it in some arcane way
does so, why doesn't the operating thermostat open first and thus keep
the water from getting hot enough to pop the thermal overload?

I repeat, it has to be caused by a stuck operating thermostat, most
likely the lower one.

Happy Holidays,

Jeff

(W1BSV + Brass Rat '57 EE)

"As long as there are final exams, there will be prayer in public
schools"