Suburban Hot Water Tank Repair

[Mike and Carol]

A couple of weeks ago we took a short trip to Tennessee (battery box repair at Oliver).  Our hot water tank worked fine on the way there, when we picked our trailer up after a day at the Oliver service our hot water wouldn’t work on shore power.  Propane worked fine.  At first I thought maybe the repair guys had done something but it turns out they had nothing to do with the problem.  

Before the trip I installed two new Epoch 300aH batteries and in my zeal to turn the PD4045 on to equalize I hooked up to my home 30a forgetting that I was winterized, empty hot tank but the switch left on!  The heating element burned out.  I ordered a new element, replaced the burned out element, problem solved.  So why did I not have hot water with a new element that was working fine for a week?

So, I started checking.  First was the new element, measured resistance across the two terminals with the wires disconnected and got about 10.4 ohms, so it was good.  Then I took the cover off of the thermostat switch and measured resistance for it and the ECO (emergency cut off) switch and they were both good.  You can remove the cover for the heating element but if you want to take the element out you must remove the gas tube in front of it.  To remove the cover for the thermostat switch I had to loosen the propane inlet tube that covers the bottom cover screw.  Behind the cover is a thermostat switch and ECO for the 120v side on the left and the same set up for the 12v/propane on the right.

I popped out the on/off switch and measured across the two terminals and it checked out okay.  So, I turned on shore power and measured voltage across the terminals on the back of the heating element.  I got a variable reading that bounced around between about 60v and 80v.  When I touched ground (tank mounting screw) the voltage went to a steady 120v.  So now I had to find the loose wire that was causing the low, fluctuating voltage.

I started at the fuse/breaker box under the dinette.  I checked all the connections, everything tight.  I found the cable connected to the hot water breaker and followed in down to a bundle that ran under the pantry, bed and around the back of the trailer, under the furnace and up to the hot water tank.  It looked like a continuous run so I took the cover off of the junction box where the cable connected to the tank.  Bingo!

The cable has three wires, a bare copper, a black and a yellow.  The bare copper was connected to the ground screw, the black wire was connected to the tank black wire but the wire nut was melted through to the coil in the nut.  The yellow wire was totally burned and not much was left of the wire nut.  It appears the wire nuts were not properly installed during installation, it was the first time I removed that cover.  Pictures below.

There was enough slack in the trailer cable to get to new wire.  On the tank there was no slack so I didn’t have much to work with once I cut back the burned wire.  The tank had solid wire, the cable was stranded wire.  That can be tricky.  I made sure I had a bit more of the stranded sticking above the solid so the nut would grab both.  I did a serious pull test when finished.  Hot water restored. 

Fortunately I had help during this process.  Ken @mountainoliver was answering my texting and offering sage advice while I was scratching my head and rubbing my chin trying to figure out what was going on.  Bottom line, don’t be afraid to tackle issues with your trailer!  Also, if you have a hot water tank, it might be a good idea to check your power connection.  It’s one screw and easy to do.  The simplicity of the Suburban hot water tank makes it fairly straightforward to troubleshoot and repair.  Plus, there are a bunch of YouTube videos that go over everything.

Here’s the mess I found in the junction box.  This box is on the upper right side of the tank as you are looking at it from the back bed opening.  The cover is held on with one small screw.

Another view…

One more…

What was left of one of the wire nuts…

[Steph and Dud B]

Something very similar happened to us, except they used Wago connectors in the j-box instead of wire nuts. One came loose and the Wago melted.

[rideandfly]

We smelled an acrid odor one time. When I found it, very similar wiring failure connected to the Surburban Hot Water Heater, too.

[topgun2]

Nice job, Mike.

Shame that this happened but given the age and torture that we put these rolling houses through, I guess that it should not come as a big surprise.

I'd guess that you are now good for another ten years or so.

Bill

[Wayfinder]

Sounds like a new inspection item to put on my list.

Thanks all for sharing.

[Mike and Carol]

7 hours ago, Wayfinder said:

Sounds like a new inspection item to put on my list.

Anyone with the Suburban hot water tank should check their power connections annually. Had I checked I could have caught the issue before the meltdown.  I’m sure it’s been going on for years.  One screw is all that is holding the cover on.  Mike

[jd1923]

15 hours ago, Mike and Carol said:

Anyone with the Suburban hot water tank should check their power connections annually.

I'd prefer not having another maintenance item, but thanks to Mike, next time our Oliver is home for service I will certainly open this junction box, remove all wire nuts and electrical tape, strip wires down to good copper, or replace wiring if necessary, and use butt connectors! Wire nuts and Wago connectors are not automotive grade! I've never used Wago products and likely never will. Wire nuts are for 120VAC residential solid-core wires. Wire nuts will not hold stranded wire effectively!

Butt connectors are designed for stranded wire in automotive 12VDC systems to hold properly with movement/vibration. Another No-No is using ScotchLoks to add a wire. When I need to connect a third wire, I use a butt connector one size larger. Fold the wire to double thinkness on the side that has one wire.

I had a boss years ago who said during a team meeting, "Anybody using ScotchLoks in installations will no longer be working for us!" OTT uses them often too and I remove them as needed. 😒