SW10DE water heater blues - Montana Owners Club

rfdbrown32166 · 03-04-2016, 08:23 AM

I replaced my LP gas valve on my water heater because the solenoid nearest the tank failed by a short circuit. However, after installing the new valve and cycling the system a dozen or so more times it won't light. The igniter is firing, there is gas to the valve however I can't feel the gas valve clicking on when the igniter fires. This leads me to suspect the circuit board, although I've been told the board rarely fails in the solenoid circuit part of the board. I've tested across the solenoid when the igniter is firing and the voltage seems sporadic but there is voltage there.

Does anyone know what voltage I should be seeing across the solenoids when the gas valve is supposed to be open? and should it be a solid reading?

two weeks without hot water. sigh.

BB_TX · 03-04-2016, 08:33 AM

Does it not work on 120 vac either?

I am pretty sure it should be a full 12 vdc to the solenoid. You could jump 12 vdc direct to the solenoid and see if it opens. There could be a bad/loose connection in the junction box causing the sporadic voltage reading.

rfdbrown32166 · 03-04-2016, 08:36 AM

unfortunately the 120v keeps blowing the breaker on the park post, I haven't figured that one out either. Just working on one problem at a time. I'll try jumping 12v to the solenoids and see what happens. thanks.

BB_TX · 03-04-2016, 08:52 AM

Considering it trips the breaker on AC, I would be concerned you did not get something wired correctly when you replaced it. First I would go back and double check all the wiring to the water heater before trying anything else.

rfdbrown32166 · 03-04-2016, 09:27 AM

It's the 120v heater that blows the breaker, not the 12 LP gas. I'm only on a 30 amp breaker in the park and it doesn't seem to handle much so I suspect that is why it blows. I have two electric heaters running as well. For installation of the LP gas valve, there are only two wires going to the solenoids, and they are exactly where they were on the old valve (I took a picture before and after) so I know they're right. I'm on try number 30 now for the igniter to light the water heater, so I'm pretty sure it's not going to light. I'll keep working on it.

BB_TX · 03-04-2016, 03:27 PM

I understand that it is the 120 vac tripping the breaker. But the fact that after installing the new water heater, the AC trips and the 12 vdc solenoid does not work certainly makes one wonder. And that you are seeing "sporadic" voltage across the solenoid coil suggest you could be measuring an AC voltage with your meter set for DC. Just for grins, set your meter to AC and measure the voltage across the solenoid.

Irlpguy · 03-05-2016, 05:33 AM

Several campgrounds I have been in where I have had to use 30 amp has resulted in my not being able to use my water heater on 120V, especially if I am also using a electric heater, repeated tripping of the CG breaker will weaken it and you may only have 25 amps available before it trips. Now that has nothing to do with the 12V operation of the water heater, completely different circuits.

I would be betting on the 12V control board as the culprit. You can remove the dual solonoid valve and bench test it with a known voltage (12V) to confirm it is not the valve. The brown wire is the hot wire from the control board, that feeds both soloniods and the black to both is the ground. To test it, "momentarily" apply 12V from a battery to the terminals where the brown wires are normally connected, and connect the ground terminals to the ground side of a battery. Jumper across the two brown terminals and also the two black terminals so you are trying to activate both valves at the same time as is the way it is factory wired. You should certainly be able to hear/feel the valves activate if they are working properly.

If you have insufficient voltage or intermittent voltage from the board the solonoids will not operate properly. Some solonoid valves have a "start" voltage and a "hold" voltage as it does not take as much voltage to keep them open as it does to open them, this is a current saving method. If this one does it would be controlled by the board.

I would think you should read 12V DC or a bit more on the brown wire when the cycle starts and the igniter is working. If you do not have 12V throughout the cycle there must be something wrong with the board, or it is dropping because it has the "hold" feature, certainly should not be less that 10.5V or so. There is a possibility there could be a poor connection with the brown wire at the board, I doubt it is soldered to the board as it is a replaceable item.

If as I suggested above you confirm the valves are not the fault then it has to be the control board or power to or from it.

Hope you find the solution, it can be very frustrating.

rfdbrown32166 · 03-07-2016, 02:15 PM

Well, I wound up ordering a new board, best to have it around, even if I don't need it right now. I've done the checking and the valve works great so it is either the board, or possibly the wire. I don't feel like pulling out the wire right yet so I'll test it with the new board then check the wire. It's a good thing the campground has free hot showers.

cpaulsen · 03-07-2016, 10:55 PM

Had the same problem when I had a Cougar quite a while ago. Fried of mine had the same water heater in his 5th wheel......he offered to let me try his cicuit board to make sure it was the problem. Only took a few minutes and the water heater worked great. I then bought a new board.

rfdbrown32166 · 03-13-2016, 12:52 PM

Today I replaced the circuit board and viola! HOT WATER. I appears that when the solenoid closest to the water heater failed that it somehow caused the circuit board to fail also, or maybe it was the other way around, I don't know. However, it required the replacement of both the gas valve and the circuit board. I would have replaced the damaged solenoid rather than the whole gas valve but the solenoid was so badly melted and deformed that I was unable to remove it from the valve. I've set it aside to work on at my leisure. It sure is nice to have hot water again. So now, every single item in my Montana has broken down and either been repaired or replaced except for my gas stove. I think I'm becoming an expert. lol. Thanks again for everyone's advise, it is invaluable.

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