Those darned water heaters!

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flylooper

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Joined
Sep 26, 2017
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Location
Leaburg, Oregon
I have a Suburban SW6DE elec/gas 6 gal. direct spark ignition water heater in my trailer. For some reason it's getting really temperamental in how it cycles on and off.  Recently, it began not cycling on when it runs out of hot water unless I totally disconnect the electricity from the battery and then re-connect the battery to the trailer's circuitry. It turns itself off okay when the water has reached the correct temperature, but once depleted of hot water it won't turn back on.

This is a mystery to me and I'm not sure where to look for (what I think is) the electrical problem: Bad/loose/corroded connection? Does anyone have some experience in this area? Any thoughts gratefully accepted!

Thanks,

Bob
 
The low side thermo tab is probably bad. The high and low are sold as a package and easy to replace for the outside.
 
Thanks! Looking at their parts list (http://bigdiscountrv.com/breakdowns/suburban-model-sw6de-parts-breakdown), it appears to be what they call "Switch assy, 12 V.D.C. Thermostat/Hi-Limit" Part No.232282. There is another assy for the 120 V.A.C. (p/n 232306)

There doesn seem to be a lo-limit switch.

I'll give them a shot. Fingers crossed... :-\
 
Note being propane and electric it will have both a 12V and a 120V switch assembly the 12V is for when running on propane.
 
I wouldn't jump into throwing parts at it without a firmer diagnosis. Get a Suburban SW series service manual at http://bryantrv.com/docs2/docs/subsw.pdf

Is this problem LP only, electric only, or both?  When in LP mode, does it attempt to light? If the LP burner attempts to light and fails, or the flame sensor thinks it failed, the control board "locks out" and won't restart until the power switch is cycled.
 
As usual Gary gave the best advice and I'd like to expand on that a bit.  If it tries to light but fails the problem is almost always junk in the gas path.  Most often it's spider web.  Spiders love propane.  Who knows why or what it does to them.  I've fished massive egg sacks out of propane appliances.

The suburban gas path is easy to take apart, clean, and re-assemble.  Just be careful not to lose any screws.  Alcohol works well to clean the orifice/jet, a small rag with alcohol works for the tube  I use a guitar string to chase the actual orifice but just about any thin wire will do the trick.

The other areas to check are the flame sensor and the air mixture setting.  Also easy.  The troubleshooting section in the manual is quite good at describing a healthy flame.

Good luck.
 
Well, I've replaced that high side thermo switch and the interior onn/off switch, flushed out the tank and replaced the anode rod (Not really germane to this problem) and hopefully that'll solve the problem. I know it's not a gas problem because when it fires up it works just fine. The problem is getting it to fire up after the initial heating of the water, as I mentioned at the top of this thread. I'm going to test it today. The batteries have been on a drip charger for the last week.

One thing I did notice is that the 120V side of the tank is kind of messed up. The on/off switch is frozen in the off position. I suppose I could dig into that problem but I think I'll just let it go as I always just use propane when I'm away.  I really don't want to install a complete new heater. It's just a "fishing trailer."

I've got lots of questions on this trailer business! This is a whole new world to me.  :)
 
I doubt if either of those things would have an effect, but good luck!

There is little more we can say to help without some more specific info about what happens when it fails to cycle back on. If it tries to re-light and fails (the most likley scenario), then you need to dig into the ignition and combustion air/fuel side. If it makes no attempt to cycle back on, then it is thermostat or control board problem.

If you get the 120v side working and it cycles OK, you can eliminate at  least some parts of the heater control of the source of the problem. And if electric mode doesn't cycle either, you would know you have a fundamental control board problem.
 
Gary, it just won't cycle on when the tank temp drops to the point where, normally, the heater would cycle on to maintain temperature. Same thing after taking a shower or washing dishes. The tank won't fire up when there is cold (replacement) water in the tank.

What I discovered was that, when I disconnected one terminal of the battery for a second, and then reconnected it, the heater fired up as normal. Something isn't telling the tank to fire up when it needs to.  Hopefully, it's that part I replaced.  [scratching my head!]

Bob
 
I get that it doesn't fire up, but not the specifics of what does or doesn't happen. Have to get down to finer details to do a better diagnosis. Removing power does a reset of the entire system, of course, but we still don't know what wasn't working in the first place.

Best of luck, but I predict no joy from the actions you outlined.
 
I suggest that you jumper across the two thermo switches in one of those situations where it doesn't relight after using all the hot water.

Find the control board, on 3 of our RVs the control board was held to the top of the tank insulation with double sided tape.  Pull the board outa of the edge connector and clean the contacts with a pencil eraser.  Then re-seat the board and try again.
 
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