LP Electrodes will not stay lit

[Wicklow]

Water is in the heater, all switches are on, breaker is not tripped, good and steady flow of propane, no obstruction in the burner tube. Meter (if I am doing correctly) says the thermos are good? what should be the ohm's resistance and voltage be so I can recheck myself.....lol. The electrodes lite up the propane and stay lit for 5 secs and shut-off. And of course, system try's again 2X and fails again 2X. Why won't she stay lit?

 

[danemayer]

There's probably a flame sensor that tells the control board ignition was successful and then the control board keeps the gas valve open. So I would think the possibilities are 1) out of position flame sensor 2) wires off the flame sensor at the sensor or board, 3) bad sensor, or 4) bad control board.

 

[Wicklow]

There's probably a flame sensor that tells the control board ignition was successful and then the control board keeps the gas valve open. So I would think the possibilities are 1) out of position flame sensor 2) wires off the flame sensor at the sensor or board, 3) bad sensor, or 4) bad control board.

WOW, just you're reply, where is everyone??? Still partying from New Year's Eve.....lol. Correct me if I'm wrong please, but I'm calling the "garden tool" looking like part w/the 2 arms that prong down and engulfed in the igniting flame "electrodes". Is that the same as what you call a "flame sensor?" And if different, what does the flame sensor look like and exactly where is it positioned? I could not find the location of the part in the Manual.

 

[danemayer]

I think Suburban combines the flame sensor function with the electrode. After it sparks to ignite, the same wires carry a small current back to the board to let it know that ignition was successful.

 

[Wicklow]

Ok, but after she ignites she only stays lit for 5 ecs and shuts down, then 2 more try's and same thing, shuts down. Why won't she stay burning? Might you know the culprit/problem? Thx again!

Sorry Dan, you gave me options to look at already. I have no idea where the control is but appears inside the coach underneath the sink and maybe attached to the rear of the water tank, so that is a headache "if" that is the culprit? Maybe my flame sensor/electrode is bad? But to diagnose, then she could still be bad even tho she lites up right? For mine lites up 3X trying cycle, but fails to stay lit. Might you know what the Ohm's resistance should be on the flame sensor to be a good part?

 

[danemayer]

Water heaters are usually located on an outside wall where the cover is easily removed. The electrode/flame sensor is going to be located at one end of the gas tube. I think this is all easily accessed from outside.

I'm thinking the reason it lights for 5 seconds and then goes out is that the control board isn't getting a signal from the flame sensor. As a safety measure, the board is programmed to take that as meaning that gas is flowing, but hasn't ignited. If it allowed gas to continue to flow, you would soon have explosive conditions. So it shuts the gas valve off and tries again after a short delay. After 3 tries, the board is programmed to go into a safety lockout condition. To clear that and try again, you have to turn the switch off and back on.

It could be the electrode/sensor, or perhaps the control board is failing. The electrode/sensor costs about $14. The board is around $75.

If you want to test the sensor, here's a video that shows how to test the sensor on a Suburban Furnace. The parts involved are similar, and in fact Suburban makes a replacement board that can be used either on Furnace or Water Heater.

I'd probably just spend the $14 on a new electrode/sensor and see if that fixes it.

Sorry, I haven't replaced one myself, but you might do a search for videos on how to do that.

 

[JohnDar]

Here's a Suburban Water Heater service manual. Start on Page 10.