On 11/10/2010 9:45 AM, RBM wrote:
"Tony wrote in message
...
My girlfriends water heater goes cold as she runs a bath. (It used to
give plenty of hot water for 2 baths.) Twice now as I opened up to get to
the thermostats it decided to work and was OK for one bath. It's an old
fashioned unit that is in a white porcelain cabinet in the kitchen so I
can't leave it open for safety reasons.

When I did open it, the lower element was on (240AC and making the noise
they make) and would switch on/off with the upper thermostat.

I'm guessing a bad thermostat (electrical connections are good), any idea
which one?

What if one thermostat is off a bit? Can I turn one a hair higher than
the other and if it doesn't work put it back and turn the other one a bit
higher? Does that make any sense?

Now that I think of it, if the upper thermostat turns on while I'm bumping
it as I'm opening it up, that is probably the bad one....?


The upper thermostat sends power to the upper element, once it's satisfied,
it disconnects from the upper element and sends power to the lower
thermostat, which in turn sends power to the lower element until it's
satisfied, at which point it opens the circuit to the lower element. Without
an ammeter, you can't easily tell if the elements are heating to capacity,
but it does sound like, from your description that the upper thermostat is
faulty


Thanks for the tutorial on the operation, I never worked on one before,
just replaced leaking ones. It sounds much easier to diagnose now.
(And I do have an ammeter that goes up to 20 amps if needed.)

Tony