Nonnymus wrote:
Our 3-month old Kenmore 50 gallon water heater had a problem Thursday.
After installation, I adjusted the heat so that we got 135f water, and
this worked great until Thursday. Thursday morning, I ran the hot water
in the sink while brushing my teeth, so that the shower would be ready.
When I rinsed the toothbrush, I literally scalded my hand. My IR
thermometer showed 190f water. I immediately went to the garage and
turned the gas valve down to pilot. It was set where it was supposed to
be, by the way.

We called Sears and they said they'd have a technician out next week.
In the meantime, I left the valve on pilot. By this evening, the hot
water in the tank was exhausted, so I intended to turn the valve back up
and watch it closely to get another tank of hot water.

Instead, the pilot was out. By depressing the valve, I can light the
pilot, but even after a couple minutes, the flame will not stay lighted
when i release the button.

1) Is there any "trick" to getting the main burner lit temporarily,
under manual observation and control?
2) Do you think that the overheat condition has toggled some internal
safety in the gas valve? Can it be reset?
3) What might have caused the overheating in the first place? The PT
valve never tripped, by the way.

Nonnymus

Good one. You have hit the nail on the head!

There is indeed a safety overheat internal to the gas control.
If it senses out-of-bound water temp (or even an empty tank
which has overheated) it trips the circuit to the thermocouple
open. That's why you could light the pilot but it won't stay
lit and the main gas valve won't open.

Once the safety has tripped, the game is over; it is a one-shot
affair.

It would seem you have an iron-clad case against Sears and they
should replace the entire gas control without argument (you hope).
The tank needs to be drained to do this.

Jim