WATER HEATER STUCK ON

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WATER HEATER STUCK ON

October 24, 2017, 08:29:15 am

Super-heated water was gushing from the water heater's TP (Temperature-Pressure) valve. No wonder...it was scalding hot. The only thing that I may have done to caue this was to cycle the 12 volt power off, then on in one second, possibly confusing/damaging the "dino" circuit board (AKA Dinosaur electronics control board). Last night in the dark, I verified the TP valve is good and thermostat is good. Today I will test the dino board. I have a spare furnace dino board, which should be adaptable to the water heater. My question is:

Has anyone ever seen the water heater stay ON uncontrollably when 12V power had a one-second interruption?

We are currently in Nashville on our nine-month USA tour.

Re: WATER HEATER STUCK ON

Reply #1 – October 24, 2017, 08:42:44 am

Quote from: Tim – October 24, 2017, 08:29:15 am

Has anyone ever seen the water heater stay ON uncontrollably when 12V power had a one-second interruption?

It's always something new and interesting to keep you "involved", ain't that right?

Have to say I don't recall reading anything on our Forum about this mode of failure. I'll look around...

What water heater do you have? There is one or more thermostats located somewhere on the tank. I would think they would be prime suspects in this case. No thermostatic control = runaway heating element? But you say you already tested them...

There is also a thermal fuse that should have opened if water temp was excessive... Guess it also failed?
Ahh...reading the manual, I see the thermal cutout only applies to faulty gas burner operation. Was your heater running on gas?

Did you try unseating and reseating the connectors on the circuit board?

Re: WATER HEATER STUCK ON

Reply #2 – October 24, 2017, 08:48:46 am

The Atwood manual trouble shooting section doesn't really cover your problem, except suggesting to reseat or replace thermostats:

Atwood Water Heater Troubleshooting

Re: WATER HEATER STUCK ON

Reply #3 – October 24, 2017, 10:23:49 am

Replacing the card would be the first thing, but I've never heard of or had a "gusher". Is the HWH original?

Re: WATER HEATER STUCK ON

Reply #4 – October 24, 2017, 10:50:07 am

Problem solved, I think. Did the following:

1. Dried out the hot water and wet bay.
2. Read resistance of the thermostat and thermal fuse. Both read near zero ohms, so they are good.
3. Reset the 12 Volt power to the Dino board by unplugging the connector.
4. Ran the water heater, good flame.
5. Unplugged the thermal fuse. System stopped. Good sign the dino board is good.
Note: The thermal fuse shuts down the system if it is exposed to 190 Farenheit. (E.g. If the flame is blocked due to a nest).
6. Ran the system. Took about 40 minutes for the heater to stop. YAY!! No weeping of the TP valve.
7. Note to self: Carry a laser thermometer and a spare thermostat at all times.
8. NEVER GLITCH THE 12 VOLT SYSTEM. Shut off ALL systems, then turn off house 12 volt system.
9. If you inadvertently shut off the 12 volt system, wait 30 seconds prior to re-engaging it.

Re: WATER HEATER STUCK ON

Reply #5 – October 24, 2017, 11:00:07 am

Quote from: Chuck & Jeannie – October 24, 2017, 08:48:46 am

The Atwood manual trouble shooting section:

Atwood Water Heater Troubleshooting

This link goes to Barry's Beam Alarm site. When I try to print the trouble shooting steps, all I get is a blank page. Has anyone successfully printed something from the Beam Alarm site? What is the secret?

Thank you very much,

Trent

Re: WATER HEATER STUCK ON

Reply #6 – October 24, 2017, 11:19:16 am

Found it on another site and uploaded to the Media section here

The selected media item is not currently available.

Re: WATER HEATER STUCK ON

Reply #7 – October 24, 2017, 12:10:02 pm

Quote from: Michelle – October 24, 2017, 11:19:16 am

Found it on another site and uploaded to the Media section here

That's actually a much better reference source - thanks for once again taking care of us and adding to the value of this great Forum!

Re: WATER HEATER STUCK ON

Reply #8 – October 24, 2017, 04:52:46 pm

Quote from: Tim – October 24, 2017, 10:50:07 am

Problem solved, I think. Did the following:

1. Dried out the hot water and wet bay.
2. Read resistance of the thermostat and thermal fuse. Both read near zero ohms, so they are good.
3. Reset the 12 Volt power to the Dino board by unplugging the connector.
4. Ran the water heater, good flame.
5. Unplugged the thermal fuse. System stopped. Good sign the dino board is good.
Note: The thermal fuse shuts down the system if it is exposed to 190 Farenheit. (E.g. If the flame is blocked due to a nest).
6. Ran the system. Took about 40 minutes for the heater to stop. YAY!! No weeping of the TP valve.
7. Note to self: Carry a laser thermometer and a spare thermostat at all times.
8. NEVER GLITCH THE 12 VOLT SYSTEM. Shut off ALL systems, then turn off house 12 volt system.
9. If you inadvertently shut off the 12 volt system, wait 30 seconds prior to re-engaging it.

Regarding #7, did you have to use a new thermostat?

Re: WATER HEATER STUCK ON

Reply #9 – October 24, 2017, 05:08:19 pm

Tim,

So, what is it that caused the failure to shut down and what cured it?

That is a potentially extremely serious issue.

Re: WATER HEATER STUCK ON

Reply #10 – October 24, 2017, 08:53:26 pm

Thermostat was good because testing today revealed that it shut down the water heater after 45 minutes, when the water was hot. I believe the Dino board turned on the flame indefinitely because of my rapid 12 Volt power cycling. Lucky my wife saw water spewing from the wet bay before water heater / the rig had a melt down. The TP valve did it's job, but had we left the rig for the day, well, do you know the song "Smoke on the Water"?

My recommendation for all rigs:

1. If the 12 volt house power has been rapidly cycled, turn off the 12 volt power with the switch by the door (1997 U270), wait 30 seconds and turn it on.
2. Turn off the water heater when leaving the rig for over one hour.
3. When in the rig and the water in the heater is cold, check that the water heater has shut down after one hour. This applies to my 10 gallon propane unit.
4. Buy a spare Dinosaur Electronics board and thermostat. The Dino board can also work in the propane furnace. Bring a lazer thermometer to double check temperatures.

I will be watching our water heater like a hawk during the next five startups/shutdowns to verify my hypothesis that the Dino board got stuck on by my rapid 12 volt power cycling.

Re: WATER HEATER STUCK ON

Reply #11 – October 24, 2017, 10:02:01 pm

the only way to know for sure is to see if you can cause the same thing to happen again with the same results.......

or......... was it just a one time fluke? or chance happening?

I would have thought that the high temp safety shutdown would have had to fail for this to occur.

Re: WATER HEATER STUCK ON

Reply #12 – October 25, 2017, 08:40:26 am

Is there another "high temperature safety shutdown" feature besides the thermostat? The TP valve will only relieve the pressure and water from the tank. Once the tank is dry...meltdown?

Re: WATER HEATER STUCK ON

Reply #13 – October 25, 2017, 08:46:43 am

Any chance it was simply dry?

Re: WATER HEATER STUCK ON

Reply #14 – October 25, 2017, 09:26:08 am

I'm at work now, so I don't have a photo available, but our 10 gal propane/elect/motoraid - Atwood has two small round "clicks-on" preset thermostats, one is set at 160* for normal control and the other is set at 180* for a hight temp shut down if the other fails.
If the gas valve fails open? And flame wont shut off? Not sure of the results then.... But most likely not good things will happen.
That is why I make sure water heater is off before we leave the coach.

Re: WATER HEATER STUCK ON

Reply #15 – October 25, 2017, 11:01:13 am

Quote from: Tim – October 25, 2017, 08:40:26 am

Is there another "high temperature safety shutdown" feature besides the thermostat? The TP valve will only relieve the pressure and water from the tank. Once the tank is dry...meltdown?

TP valve should seat itself again once pressure or temp is reduced. Assuming city water or tank pump on, the heater should refill as TP let's stream/hot water out.

Re: WATER HEATER STUCK ON

Reply #16 – October 25, 2017, 09:26:29 pm

It's a good idea to open the TP valve occasionally, just to make sure it is fully functional. It needs to open at the proper temperature/pressure, and just as importantly it needs to close and seal tightly when tank conditions return to normal. While I was working on our water heater, I attempted to open the valve and found it was totally frozen. It would not budge no matter how much force I used. It looked like it had been in place for a long time - it could have been the original one installed at the factory.

I searched for a replacement - I couldn't find one locally, but did find it online. If yours looks questionable, might be a good idea to replace it. Cheap insurance against a water heater disaster!

See link below for part number and the source I used:

Hott Rod Installation, Atwood GH6-7E

Re: WATER HEATER STUCK ON

Reply #17 – October 25, 2017, 11:58:29 pm

Quick video of a water heater and a failed TP valve:

Mythbusters Water Heater Explosion - YouTube

Re: WATER HEATER STUCK ON

Reply #18 – October 26, 2017, 02:33:19 pm

even worse - 2 people were killed 500 feet away
St. Louis boiler explosion: 4th person dies - CNN

Re: WATER HEATER STUCK ON

Reply #19 – October 26, 2017, 02:57:43 pm

While its certainly a good idea to test your temperature & pressure relief valve periodically, I would strongly advise not doing the test on a Friday afternoon, or while boondocking as they have a tendency to stick open or leak from grit on the valve seats. Pretty sure they still function if the handle does not move, but I would not bet on it. The other gotcha is if you have to replace it you could damage the tank connection or threads.

Re: WATER HEATER STUCK ON

Reply #20 – October 26, 2017, 08:44:11 pm

Agree that there are two thermostats on the tank. Makes sense since a primary thermostat failure would be catastrophic. A second thermostat to shut down the gas flow makes perfect sense.

The gas thermostat is labeled ECO. Would that stand for Emergency Cut Off?

Re: WATER HEATER STUCK ON

Reply #21 – October 26, 2017, 10:44:41 pm

E.C.O. = (Energy Cut Off)

The definition is found in the manual linked above, Reply #6.

Re: WATER HEATER STUCK ON

Reply #22 – October 27, 2017, 01:36:51 am

Holy cow, I omitted a key word do NOT test the T&P when another is not readily available.

Re: WATER HEATER STUCK ON

Reply #23 – October 27, 2017, 05:11:55 am

Fortunately, the TP valve correctly re-seated with no dripping. Perhaps the TP valve was pretty clean because it was recently flushed with vinegar. I thought the tank was toast because the super-heated water and steam was gushing uncontrollable for five minutes. I am confused why the ECO did not close the gas valve when it reached 180 F. The TP valve has a temperature rating of 210 F, and there was boiling water spewing out.

Re: WATER HEATER STUCK ON

Reply #24 – October 27, 2017, 08:42:52 am

Quote from: Tim – October 27, 2017, 05:11:55 am

I am confused why the ECO did not close the gas valve when it reached 180 F.

Several logical possibilities:
1. The ECO did not sense the abnormally high tank temp, due to improper seating.
2. The ECO did sense the high tank temp, but did not respond (defective ECO).
3. The ECO did sense the high tank temp and did respond, but this response was not conveyed to the circuit board (bad wiring or connector)
4. The ECO did it's job perfectly and successfully notified the circuit board, but the circuit board dropped the ball (defective circuit board).

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