We're no strangers to fixing things on the RV, particularly the water heater. So, when we suddenly had no hot water from our mostly brand-new water heater, at least we weren't jumping into new territory.

For the record, this is the same water heater we had on our last RV (397TH), which is the Suburban 12 Gallon SW12DEL.


The first step was to isolate the problem. Our water heater has electric (120VAC) and Propane (12VDC) as heat sources. Turning on the propane side of the water heater, we got hot water very quickly. So, I knew the problem was isolated to the 120V (AC) side.

I started at the heating element itself, taking a voltage reading, and there was no power to the element.

From there, I went to the other end of the AC circuit and tested the power relay, where 120V comes from the distribution pane to the water heater. All good there!

Next was to move down the line from the relay to the thermostat. I opened up the panel to take some readings, and it was immediately apparent where the problem was!

The Problem!

As I took the cover off, I could see the connector coming into the thermostat from the power relay was melted entirely and fried! With that, the first step was obviously to replace the fried connector. As I pulled the wire out, I could see the root cause of the problem: the wire had rubbed on a sharp edge of the case, shorted to ground, and burned up the connector. I was hopeful that the thermostat itself was still in good shape, but I wasn't that lucky!

I replaced the connector and ordered a new thermostat and a spare!

NOTE: From a comment by @douglascounts5851 (Youtube): “.. if the internal wire itself was touching the case, the wire would have melted right there. The impression you saw on the wire insulation was simply caused by pressure on the wire near where it had been heated up. Also, you can see that the wire had hardened near the connector which also indicates that was near the source of heat. A few different things can cause this, one would be if the connector was loose as any arching within the connector can do this. Also, if the contact in the thermostat (which I think caused this) wasn't completely closing properly, the arching inside the thermostat will generate a great deal of heat. You see this a lot with contactors, thermostats, and other switch types that don't close completely or have degraded/burnt contact points.”

My Thoughts: This is definitely a possibility. But, looking back at the footage of the cut in the wire, it sure looks like there's charred conductor and melted insulation, with a clear hole all the way through the insulation (at 4:24 in 4K, you can see it). Perhaps the thermostat was weak and a short pushed it over the edge… Or maybe a bad thermostat caused the wire to get hot enough to melt where it was against the case, causing it to melt some then short. No way to know 100%.

The Fix!

Replacing the thermostat was extremely easy, but I also wanted to fix the root cause: the sharp edges. I could see where Suburban had bent the case edge back, so I decided to expand on that method, bending the whole top and bottom edges out of the way.

I buttoned it all up, and we were back in business!

Suburban's Response

I submitted a question via Suburban's website and had a call and voicemail response about 2 hours later! Impressive! My primary reason for contacting them was to make them aware of the issue, and they were very receptive to that, saying, “If we do something wrong, we want to know about it.” They said they would make sure to let the manufacturing side be aware and check that area on units in production and going forward.

Additionally, I wanted to ensure that warranties would not be affected if we recommend people check that area behind the thermostat panel. Again, the response was very good: “We aren't looking for ways to void warranty claims,” and said it's OK to look in there but get any service or repairs done by an RV service professional.

While no one wants to have their water heater break so early on, at least it was an easy fix! Plus, I do kind of like the process of troubleshooting issues. 😊

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