Water Heater on Electric Problem

Found the problem. It was a relay that is used to turn power on/off from a switch in the kitchen.

Do as shastagary described. If the switch is stuck you can guarantee its melted inside and that is where your voltage issue is. Once you've done it you'll see how easy it really is. A bent screw driver can even make it easier to get under the outside lip of the switch. The ends of the switch are spaded and it's just an unplug the old and plug on the new and stick it back in the slot.

taking things apart to check voltage at the tank switch would be a real major pain anyway

the switch can be pried out from the outside with a screw driver make sure the breaker is turned off first i had to replace mine this spring it is not hard to replace and does not cost much.

In very hot weather, our 15K A/C runs all day and we have to be very choosy about other 120 VAC loads. I replaced the 1440W element in our Suburban with a 1000W and it helps to an extent, but I usually use LPG in summer. That's when I learned the value of a DSI water heater! If I click it ON when we sit down to eat, there's plenty of HW for dishes by the time we get back up. We use the campground showers, so I don't know how much less HW the 1000W provides than 1440W does, but for our use, less wattage is a good deal.

Dick_B wrote:
I had to replace the switch and found some wires melted. Repaired everything but had to remove the WH to do it. Also found we would blow a C/B if we were heating water with electric and had another current hog, like a coffee pot, on at the same time.
So now I heat on propane and keep the electric as a backup.

Bad switch, melted wires all too common. Replaced my 12 year old Suburban last summer for the same problems. Switch frozen, bypass the pesky thing. Melted wires, replaced them. Failed for the third time and got fed up. New water heater from best converters was pretty cheap, so out with the old, in with the new took me only about a hour.

I had to replace the switch and found some wires melted. Repaired everything but had to remove the WH to do it. Also found we would blow a C/B if we were heating water with electric and had another current hog, like a coffee pot, on at the same time.
So now I heat on propane and keep the electric as a backup.

Sounds like your WH might be same as ours, Suburban SW6DE. Amazon has the "Suburban 232259 Electrical Element Switch - SW Series." Just looked at a heater yesterday where the switch no longer moves. Ours probably doesn't either, but we have an inside wall switch.

Ours wasn't heating on electric, and I was sure it was the Element. I'm usually a better troubleshooter than this, but I MISSED the open connection in the punch-down splice box in the cabinet, at the rear (inboard) end of the water heater. Suburban puts the heater's connection box where it falls right at the inside wall of the coach body. Jayco ran a short wire from there, to a punch box fastened to the kitchen floor. One of its connections had burnt out. In my case, it was the White/Neutral wire, so I was finding voltage all the way to, and across, the Element. ACROSS should have been my clue. Hot TO it, OK. Hot Across it, Bad. Circuit wasn't complete back to the Neutral side of the Breaker panel.
A new Box, punched down carefully, probably would have been an OK fix. Having Wire Nuts, I simply gutted the Box, cut out the plastic that supported the connections, and used it as a Splice Box for Wire Nut connections. I twisted the solid copper wires together with pliers before putting the wire nuts on, and also wrapped the nuts to the wiring with electrical tape.

It is the BLACK that is switched and if the ON/OFF is stuck ON, odds are the switch is melted. Yes, the Black goes thru that switch. Make sure you get a Suburban replacement switch, as most switches you will find aftermarket will not be rated for the AMPS going thru the switch. Doug