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Jim77_and_Jamie's avatar
Aug 07, 2015

Troubles with Suburban SW6DEL Water Heater

This water heater is in a 2014 Outback 298RE. With the LP gas heating the water if the 120v. element is turned on, the following cycle when heat is needed the LP will not start. Tests that I have done so far.

With everything turned off and water system full and pressurized, I turn on the LP gas switch in the camper. At that time the light on the LP lights up BUT so does the 120v. switch as well, even though the switch is off. The default light goes on at this time also. After the LP ignites the default light goes out as does the switch for the 120v. (So the question here is why did the 120v.light go on?)

On the next test I did the same as above, but now I turn on the 120v. element and the light on this switch goes on as does the default light as well. The switch at the bottom of the heater is on as well. I know that the element is working because I have a kilowatt meter in line and am drawing 1369 watts to the water heater. So I have 120v. and LP gas heating the water at this time. I let the tank heat up and the LP gas shuts off first then 120v. During this test the default light never goes out. To continue this test I run cold water through the heater till heat is called for... with both gas and electric left on as would be the case normally I watch to see what happens. The 120v. turns on and after 5 minutes of waiting the LP gas never fires up. (So why does the system cycle the first time but the LP will not start on the next cycle?)

I have replaced the electronics board and repeated the tests and then replaced the 130 degree thermostat and ran the same tests... no change

I have not bought the 12 volt thermostat yet as I feel this is also o.k.
ANY IDEAS????

4 Replies

  • j-d's avatar
    j-d
    Explorer II
    A wire or connection can get physically hot, but whoever said "hot ground" might mean the polarity of the wiring got reversed. Your 120-volt-AC wiring has "hot" (black wire) and "neutral" (white wire) and switching them can cause problems. In a 12-volt-DC system, Battery Negative is Ground and is connected to the RV chassis. Battery Positive is commonly called "hot", so this person could be referring to the 12VDC aspect of this water heater (controls, logic board only, water is heated with 120VAC or LPG, not 12VDC). If the heater wasn't grounded, or 12VDC was connected instead of Battery Negative/Chassis Ground, I can imagine the logic board could get confused.
    We have SW6DE, and I'm not sure what your "L" means. On ours, neither 120VAC heater nor LPG burner is temperature adjustable. Suggests to me that whichever was set to cut off hotter would prevent the other from operating, since its temp setting was already achieved.
    Do you have a Meter? This kind is called a Digital Volt Ohm Meter (DVOM).
    Ground black to the Chassis and see if what should be +12("hot") actually is. Then see if there's voltage from water heater cabinet to that same chassis ground. There should not be. Then check for continuity from water heater cabinet to chassis ground. There should be.
    If I had to guess, 12VDC hot and ground might be reversed at the heater. But more likely the thing isn't grounded.
  • Well the saga continues. The last person I talked to said have you checked for a hot ground. So that must be reverse power back feeding a switch to make it hot???? correct??? How do I check for that? anyone???
    jim77
  • So, I've been turning my Electric on - and no matter what I do, I can't get the LP to fire concurrently.

    I woke up the other morning, and found water all over the floor - along with the water temperature extremely hot.

    I figured there was something wrong with the high temp - so I switched back to running on just LP.

    No Joy.

    After disassembling my access cover for the reset high temp, I found the electric heater circuit bolt (which holds the high temp and shut off at 130), the spot weld had failed.

    Sigh.

    Once I reset the LP, it fired right up.