Water heater won’t light

ezincolo

Uh boy,

First plumbing now electrical. For those readers keeping score, this is the same new Suburban water heater that I had plumbing issues with (Post "New Suburban water heater won't fill") but resolved thanks to help from Forum experts

But now the WH won't light. Here are the details:

I installed a new Suburban WH (gas only), hit the WH switch and heard the burner light. The tank was empty so I turned it off immediately. After going through the plumbing issues detailed in the earlier thread, I got the tank filled, hit the reset button on the face of the WH, toggled the WH switch in the coach and the "pilot out" light went on. I cycled the switch a few times (per the manual) and this light went off, but no ignition.

I got down and checked the three wires you have to connect to the WH for installation (red, blue and yellow). I used crimp connectors - which I'm not crazy about (and Ray isn’t either !) although the coach is full of them - but thought maybe one was loose. So I gave each a couple tugs. I also read about cheap controller boards failing (burned component) so I opened the controller board enclosure, checked the board, the multi-wire connector and the high voltage wire to the ignitor. Everything was good so I screwed it back to the wall.
I guess I'd left the WH switch ON because about 10 seconds later the burner lit. Woohoo!

Assuming the crimp connectors were indeed the problem, I turned off the WH switch and decided to go outside and solder those connections (can't reach wires from the inside). Before I did this I wanted to hear the burner light again, so I turned the WH switch back on - no joy.

I went ahead and soldered the connections anyway and tried the WH switch (after hitting the reset button again) - nothing. But I didn't get the "pilot out" light either, which I had been seeing every time I tried to get ignition.

For the record, I’ve got 12.8 V across the poles of my coach battery. I’ve also checked the fuses several times and nothing is blown.

At this point I'm out of ideas. Does anyone have a suggestion?
What am I missing?

Thanks a lot.

Eric

Ray

↪ezincolo

I'm wondering if maybe there is a faulty/flaky high limit or thermostat swtich. I'd check to make sure the 12VDC is getting through them.
Here is a video I did on my unit when one failed hampered electrical operation
https://www.loveyourrv.com/rv-water-heater-not-fully-heating-failed-130-degree-thermostat/

ezincolo

Yeah, I checked it this am and it was ~1.5V So, I’ve got a bad connection or ground I’m thinking
Curious how that could happen with a new appliance
Oh well
Thanks for the input Ray

Eric

Ray

↪ezincolo

Best of luck, and let us know what you end up finding out.

ezincolo

Ray,
I chased the voltages thru the system and got the following results:

Verify you have 12VDC TO switch - CHECK
Verify you have 12VDC from switch to/thru set of t-stats - CHECK
*t-stat closes at 100*F water temp/opens at 130*F
Verify you have 12VDC on Red wire at circuit board - CHECK - I took this reading from the multi-pin connector that connects to controller board.

At this point you should have 12VDC to gas valve....both solenoids - NO!
AND Sparking from Electrode ---- 1/8" spark gap - NO SPARK

At this point it looks like I've got a bad controller board. Would you agree?

Ray

↪ezincolo

Sure sounds like it.

ezincolo

Hello Ray,
Well, I replaced the controller with a Suburban-branded part thru Amazon and got the same results. To reiterate: See attached diagram of Suburban SW6D

- 12.5V across red and yellow wires going to controller board.
- 0.0V (not a few mV) across brown wire and ground. Brown wire comes from controller board thru its connector and the ground is taken at the point where terminals #3 and #2 at the box labeled "gas valve" connect to the body of the water heater.

I can't imagine the gas valve is bad. But if that's the case, I need to return it to Amazon this week, since the 30 days runs out on Friday. It was a brand-new, factory packed Suburban WH, all the pieces and packing.

Thoughts?

Thanks
Eric

Ray

↪ezincolo

I found this service manual online - https://myrvworks.com/wp-content/uploads/2020/04/Suburban-Water-Heater-Service-Manual.pdf May help if you haven't seen it as it goes more in-depth than the user manual

ezincolo

Wow, excellent. This may really help
Thanks Ray!

Eric

ezincolo

Hello Ray,
Well, FINALLY, got this thing figured out. :joke:

Turns out the problem was in the control panel, specifically, the Water Heater ON/OFF switch. Apparently, the switch was intermittent, - old contacts in the switch and 25 years of dirt, etc.
Also, the "Pilot Out" light would occasionally NOT illuminate when it was supposed to be ON, even though it was sent 12V from the controller ckt board. Between these two issues, I couldn't nail down what was going on. It makes sense, since the control panel on this rig is on the exhaust hood - go figure. What's the chance there would be dust or grease or other stuff in this area to muck up these old electronics (25 year old Class C). :angry:
Anyway, I cleaned the contact and connections and all is well.

On the bright side, I got a crash course in RV wiring and plumbing, so there's that.
I really appreciate your help, sir.

Thanks
Eric

Ray

↪ezincolo

Awesome, thanks for the update!

Water heater won’t light

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