I've got a Suburban SW10DE water heater in my new-to-me 40' bus. It's the kind that does propane and 110ac. I didn't know anything about these when I bought the rig, but as it needs most of its subsystems overhauled, I figured it would be just another thing to learn about as I went along. I was right. When I got around to sorting out why the propane worked but the 110ac did not, I got a fair education in RV water heaters. Follow along . . .
The water heater has a short (9"), 1440w "High watt density" electric element. The element has two wires on it. A black one comes from a thermostats/high limit switch. Working backwards, the thermostats is connected to a small, 15a rocker switch that lives on the tank housing in the lower left quadrant of the hatch.
From there (working backwards) the wires run to a junction box on the outside of the tank insulation, easily accessible on my rig through the basement hatches. The chassis wiring connects to a more traditional looking AC switch on the control panel way up front above the stairwell. That switch is fed by the breaker panel (breaker 4, left side). The switch is a two-pot footprint, but the second switch location is filled with an indicator light.
That was the setup, in case a reader can use a description of the layout. Now the event:
When I bought the bus (2001 40DP Mountainaire) for $9500, I knew I was going to pay the difference between the purchase price and a functional home in repairs, overhauls, and upgrades. That's how it works -- pay the big bucks up front and get something nice, or buy an unloved one and pay the big bucks over time making it yours. Among the nonworking "appliances and accessories" (per the owner's guide tabs) was the a/c side of the water heater. The propane side worked, but it's expensive and problematic to get more propane when the bus is not drivable. They won't come to me, and I can't manage more weight than a bbq tank. So I felt the need to fix the electric side.
I assumed the water heater hadn't been serviced for several owners, and that it had probably been electrified with no water in the tank by someone just pushing buttons during sales attempts. So I ordered in a new anode and a 1500w element. That and a good flush should be an adequate tank overhaul.
After cleaning the tank, sucking the rust out of the fire tunnel for the propane side, and installing the new element and anode, I flipped the breaker. . . . and nothing. Boo! Hiss!
I did some reading on IRV2. They mentioned that little rocker switch on the tank itself. I found it. It was on. It would not go off. It was melted to a lump.
I pulled it and ordered another. In the meantime I found a 15a toggle switch in my stash and installed it loosely, on account of it didn't fit the hole. Incidentally, neither did the replacement switch. If you're reading because you have a bad switch, be careful. They use two sizes of these mini-rockers on a 2001 40DP Mountainnaire, and this is the other size.
The one you want is larger, has two ANGLED spade connectors on the back, and clearly has room for a third post (but the post is not present).
Ok -- turned the breaker back on with the switch replaced and still nothing. I got the multimeter out. I could not see power at the element.
Back to IRV2 for more reading. Incidentally, that Biscuit guy knows his stuff!
I could not find a live link to wiring diagrams, but I was able to sketch out the map by descriptions in the topics. I went next to the switch above the stairwell. The light was on. It went off when I toggled the switch and back on when moved. But still no joy.
But did I feel a little gritch in the switch as I gave it that twitch? I pulled the faceplate. Pieces of shattered Bakelite rained down the stairwell. All the innards were exposed. "Well, there's the problem right there," I said to myself.
A quick trip to the hardware store (it's a common switch), and the switch was replaced. Rinse and repeat the test -- breaker on, switches on, no joy. I had power through the switch but none at the second switch.
I read some more -- circuit board controller, junction box, thermostats/high limit . . . . I was getting into the less charted territories, but I was doubling my understanding of the water heater. I probed the thermostats -- no power in or out. It seemed clear to me (finally) that my problem was unusual -- like a broken wire in the run through the chassis?
I did some more reading. I couldn't find anything directly relevant, so I decided to get in with it. I climbed into the basement bay adjacent to the water heater and examined the wiring for chew marks and damage -- found none as far as I could see. I opened the junction box and found both the black and white wires completely burned away from the wire nuts, and insulation melted an inch or so down the length of the burned ends. Suddenly I knew how my Prosine 2000 inverter had perished . . . .
I trimmed back the wires till the copper looked right and renutted them together. An hour later I was measuring 125º at the tap.
So this was a case where almost EVERYTHING was bad -- anode, element, two switches, and the wire. The only thing I did not need to replace was the thermostats, and I might do that to get 140º water.
Linear Mode
