Suburban Water Heater works great on propane but only warm on electric

Jetpilot135

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Have a 10 gallon Suburban water heater that had provided hot water (nearly scalding) in the past. Over the last two weeks have noticed that when only the electric switch is on the water gets very warm but definitely not hot. Same results at the kitchen/bathroom faucets and at the shower head. Flipping on the propane switch gets the water to hot. Thought the outside water valves on the Nautilus panel might be the issue (bleeding in cold water and so played with them for a while. But they are both fully rotated closed. Didn't really think that could be the problem since the water was hot under propane heat but didn't hurt to make sure. On the last moving day the electric was off for several hours and, on set up at the new location, I ran the water until the hot faucet was only flowing cold water. Turned on electric only and after two hours the water was back to warm but not hot so the electric does work just not as well as it did. I would think that both the electric and propane elements use the same water temperature controls but maybe not. Does any know? If this was a house water heater, I would be replacing one of the elements but I'm pretty sure that these RV style tanks only have one element. So any thoughts on how to get the electric side to heat up more? We've have been full time for 3 1/2 years. I flush out the the tank and change out the anode rod every 6 months (last time was 2 months ago) just to avoid any problems but here we are.
 
Sounds like a failing heating element to me. You can test it with a meter for resistance and voltage. If you aren't familiar with working with 120v AC, please consult a professional (I don't know your level of expertise).
 
Does sound like a bad heating element.. If you are not up to the repair, a mobile RV repair may be faster option than a dealer
 
The repair is pretty simple couple of screws and two electrical leads.

I think if you ohm it it it’s supposed to be like 55 ohms.

Bill
 
If the new heating element doesn’t correct the issue then I would be looking at the 120 side thermostat..

Both LP and 120 mode thermostats are (130 degrees +/- 5 degrees)…

They also make a 140 degree thermostat for your SW10DEL..
 
I had a similar issue with my 12 gallon heater. I replaced the 120 v. thermostat. Use a thermal paste between the thermostat and side of tank for good temperature conduction. I replaced it with a 140 degree thermostat.
 
Yes. They are independent so you can run gas and electric at the same time for faster recovery.

OK, but a single thermostat could do that. A hot water tank should only go to a certain temp, the same t-stat could very easily control both heating modes.
Didn't realize they use two.

Edit...just looked at the schematic for my hot water tank. It uses one t-stat for both 120vac and lp.
 
Last edited:
Most rv water heaters have 2 sources for heating the water: 120 v ac, and propane. The propane works off 12 volt dc for when you are not connected to shore power (120 v ac). When you take off the panel, you should see 2 physical thermostats. Mine is a suburban 12 gallon. What is your model number?
 

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