Water heater ignites then turns off immediately

[RFP]

OK, it lit and is continuing to burn with a gorgeous blue flame!

Yay!

As much as I'm against such "scattergun" approaches, I did a LOT of stuff at the same time (so, I will probably never know the real culprit). I pulled the gas valve and checked it with 12VDC to assure myself it was opening, I pulled the orifice and blew 150PSI air through it to eliminate the possibility of a clog (I couldn't see any, but, well, you know...). Then I cleaned every spade connector and ground... really, really clean.

Then, I gave it a try. It came to life and went straight to work heating the water in the tank.

Funny thing, though... when I turned the switch OFF the first time, the flame continued. So, I gave the gas valve a very scientific "love tap" and it "nearly" went out; just a hint of flame remaining.

I've since put it through several ON/OFF cycles and it has operated perfectly every time. I'm thinking all this fiddling around with the valve may have dislodged a bit of crud which kept the valve from fully closing that first time.

A HUGE Gold Star to every one of you great folks who helped me with this frustrating problem!

Robert

[CLOUD9WYO]

Found that (last item on troubleshooting list) the circuit board was bad. Upgraded to Dinosaur replacement model and no problems so far. Could be the vibration and conditions we travel in are too much for the stock model. The upgrade is clearly more robust and better protected. Would definitely check all other things first, as the circuit boards (stock and upgrade) are not cheap.

[LHubb]

This has happened to me before. You need to clean the soot off the spark probes. It works every time. Here's some photos:

[sarge12212]

First, make sure the pilot flame stays on, has ENOUGH flame (partially blocked orifice) and the thermocouple is IN the flame. If all those things look good, replace the thermocouple. If that doesn't work, replace the entire gas control. Inside of the gas control is a magnetic switch that is operated by the milliamps of power generated by the thermocouple that can go bad.

[RFP]

Originally Posted by sarge12212

First, make sure the pilot flame stays on, has ENOUGH flame (partially blocked orifice) and the thermocouple is IN the flame. If all those things look good, replace the thermocouple. If that doesn't work, replace the entire gas control. Inside of the gas control is a magnetic switch that is operated by the milliamps of power generated by the thermocouple that can go bad.

The newer water heaters do not have thermocouples. The flame it detected through the plasma of the flame at the igniter.

[JCWDCW]

Check igniter condition 1st
Others who mentioned it are right
The flame comes on then the sensor looks for heat. If it doesn't see it the gas is shut off to prevent gas build up that could cause an explosion
Sensor needs good clean connections since it is producing milliamperes of current. It has to be positioned right in the middle of the flame
JCW

[alreardon]

I had the same concern. Oddly the light is not suppose to stay on. Flashes when you flip switch only. Seems counter intuitive, but that is the way it is.

Best,

[RFP]

I just want to be clear: my problem is fixed... everything is working perfectly now. Thanks!

[waninae39]

old and new board

[perryg114]

That board is exposed to the elements. I don't see how the new board can last long without a moisture barrier.


Perry

[waninae39]

was does the AS potted board die within 6 month?

[RFP]

Originally Posted by perryg114

That board is exposed to the elements. I don't see how the new board can last long without a moisture barrier.


Perry

It comes with a protective plastic enclosure

[perryg114]

My OEM furnace board has lasted a long time. With the potted electronics I have seen some failures that I think are a result of the epoxy they pot with being too ridged and it does not flex at the same rate the board does and it break solder joints. Only time I have problems is when it is wet outside and I think that shorts out the igniter.



Glad it is fixed.



Perry

[Glenn7405]

my heater quit working 2nd trip out. Checked continuity and fuses and determined it was circuit board. Called Dometic and they shipped out a replacement board and we are back in business