what caused my 120 volt thermostat/eco switch the burn out (suburban water heater)

Bocephus · 07-27-2011, 10:25 PM

the 120v part of my SW10DE water heater quit working. i started checking voltages with the switch and breaker on....i had no power going to the heating element. i started tearing things apart and found this "link" broken. (see pics below) a few parts sites online are calling this a "130 degree 120 volt thermostat/eco switch assembly".

this must be some sort of protection device for overheating...??? im not sure. anyone know its purpose, and what would cause it to burn open like it did? (see LH side of bottom picture)

do you think i have more problems elsewhere that caused this?

Iggy · 07-27-2011, 11:39 PM

Those are the high and low limit switch that test the wall temperature. When the water is below a specific temp it will turn on the water heater gas. When the temp gets to the max it then shuts off the gas.

With the power off and wires disconnected they can be tested with an ohm meter. One set should read open and the other set should read closed when cold in the tank. When the tank is very hot these should switch. Oh. I think they are 12 volt DC and not 120 volt AC.

That's it.

Parts Link Product Listing water heater parts, Suburban-other

PS I also see where you keep your spare trailer keys.

Bocephus · 07-28-2011, 04:52 AM

Quote:

Originally Posted by Iggy

Those are the high and low limit switch that test the wall temperature. When the water is below a specific temp it will turn on the water heater gas. When the temp gets to the max it then shuts off the gas.

With the power off and wires disconnected they can be tested with an ohm meter. One set should read open and the other set should read closed when cold in the tank. When the tank is very hot these should switch. Oh. I think they are 12 volt DC and not 120 volt AC.

That's it.

Parts Link Product Listing water heater parts, Suburban-other

PS I also see where you keep your spare trailer keys.

actually, from my understanding of the system, one of those t-stat switches is for the 12v/gas half of the heater and the other is for the 120v half. if you look at that link you sent me you will see they have both 12v (gas) and 120v versions of that t-stat switch available to purchase.

your explaination of how they work seems logical...but i dont agree with the
one should be open and one should be closed" comment. i would imagine they both open and close at the same temp......then they tell their respective heat source (gas or 120v, whichever you are using) to shut off or start up. i am not 100% sure on this, but that seem logical to me.

and the picture you provided it solely for the gas/12v half of the water heater, not the 120v

cfsoistman · 07-28-2011, 06:07 AM

Suburban Water Heater Service Manual.pdf

This should explain everything about your water heater.

**KyDan** · 07-28-2011, 06:31 AM

Mine did exactly the same thing a couple years ago.
I even posted photos here.
I also found that the electric heating element was burned out.
My theory is the element burned out and shorted and took out this
"fusable" link on the thermostat.
They aren't that expensive.
If you're going to order parts be sure and check your heater element.
I bet it's shot.
As mentioned be sure and order the 120v side.

As discussed here in several other "my water heater is not heating" threads
you can get the socket to unscrew the element at Home Depot or Lowes
for not a lot of money. It's the same size socket you'd buy for a screw
in heater at home.

Bocephus · 07-28-2011, 07:19 AM

what resistance should i see across the element? i would imagine it would be best to check it while OUT of the water heater....or at least with the water drained, correct?

**KyDan** · 07-28-2011, 07:28 AM

I tried to check my element in the heater with the tank full of water
and got some "weird" reading that wasn't stable.
No matter how tight I held the test prods on the terminals the meter
would not settle down and give me a solid resistance reading.

I removed the element and it was obviously burned out.
It was bent and black with a crater in one spot.
If your element is burned out you will most likely be able to see it
without a meter once you remove it.

Don't forget to open a faucet and let off the pressure before you remove
the heater element.

If you forget you will get WET.
Ask me how I know

Bocephus · 08-02-2011, 08:24 PM

just thought i would update this for those of you subscribed, and those that may have trouble in the future and stumble upon this thread....

as you seen in the pics, the thermostatic switch is burned out. when i took it into my local dealer. my unit came from the factory with a 130 degree thermostatic link, and he told me he recommends going to a 140. as a matter of fact, that is all they stock. he insured me i would see no ill effects....only warmer water! he also send me with a heating element because he said 9 time out of 10 that is shot too. well, i pulled it out and it was nasty. i didnt even put a meter on it, it was obviously shot.

total cost with tax was 46 and some change. im sure i could have gotten it online for cheaper, but they have everything there on the spot. i installed it all in the camp ground and didnt have to use the LP side of the water heater.

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