Troubleshooting Dometic water heater in 22MLE

[Jared M]

The Dometic water heater (model GC6AA-10E) in our 2020 Imagine XLS 22MLE recently stopped functioning when on 110VAC.

I am trying to follow the Atwood / Dometic troubleshooting steps (found here). I removed the panel under the kitchen sink and see this on the rear side of the tank:



Really?! I have to disconnect water lines just to remove the junction box cover?

Has anyone else disconnected these water lines? If so, any recommendations on how to approach it? I'm solid with electrical systems but plumbing is not my forte.

[Country Campers]

Jared M

Yes that is unfortunate that you need to remove the plumbing pipes but that is the way this will need to be done.
I have copied your pic and will have it inserted below.
I circled the two black nuts on the fittings that attach to the heater you will need to unscrew these to remove the hot and cold side plumbing from the heater. Inside these fittings are rubber cone washers that you will have to make sure that you get re-installed correctly so you do not have an leaks. I also see that there is spray foam that may be attached to these pipes , hopefully they will come out of the foam with little or no resistance.
Make sure you drain the heater and have a bath towel under the fittings prior to removal. With the pipes out of the way you then can access the black box housing the electric element. Also remember to turn off all power to make sure the heater does not come on with gas or electric.

Are you sure that the element is broken and it is not the circuit board on the outside?



Brian

[Tigger1]

Agree with Country Campers to check the circuit board on the outside. Here’s a 10 min YouTube going step by step how to check:

https://www.youtube.com/watch?v=IyJW...ture=emb_title

[colan]

Not heating water on electric possible causes and how to test.

1. The switch or the wiring between the switch and the board. With the electric switch on there should be 12V at white wire on the board. Second wire on the top connector at the board. Use a metallic part on the water heater or either of the green wires at the control board for the negative probe of the meter.

2. The board - the board sends a 12volt signal to the relay in the black box on the back of the water heater. With the water heater not up to temperature and the electric switch on there should be a nominal 12v at the yellow wire on the control board - it is the second wire from the bottom of the six pin connector. If there is no power on the yellow wire replace the board.

3. If there is power at the yellow wire, go to the back of the water heater, carefully check voltage at the element. Is there 120v nominal? Yes, then the relay is working.

4. Turn off the 120v breaker to the water heater. Remove one of the wires from the element. Check the resistance of the element, should be 9 to 11 ohms.

Replacing the element - sometimes it feels like a gorilla must have done the installation. If you can’t get the element out, remove the water heater. Removing the water heater isn’t as hard or time consuming as it appears.

Another tip - I’ve found using an impact wrench to remove fittings from water heaters to be safe and effective. Trying to muscle out a stuck fitting feels like I’m putting a lot of side loading on the tank verses the circular force of an impact wrench.

EDIT: as part of step 3, verify there is 120v coming into the water heater. Check voltage at the incoming white wire and where the incoming black wire attaches to the relay. Steps like this one is where I find a non contact voltage tester to be useful. Hold the tester near the hot wire and it beeps/flashes if there is an AC voltage present. I trust these to tell me if a wire is hot. If my life depends upon a wiring being cold I always verify with a volt
meter.

EDIT 2: this for a Dometic water heater. Process is different for Suburban.

[Jared M]

Thank you for the replies!

So far I confirmed 12V at the white wire on the board when the electric switch is on. I will continue with Colan's steps over the holidays when I have more time and we're not staying in the RV. For now the water heater with works fine with LP - I just don't like 'wasting' propane when at full hookup sites.

[OurNewEra]

Thank you for the replies!

So far I confirmed 12V at the white wire on the board when the electric switch is on. I will continue with Colan's steps over the holidays when I have more time and we're not staying in the RV. For now the water heater with works fine with LP - I just don't like 'wasting' propane when at full hookup sites.

Hey Jared, I had a similar problem. My water heater worked on electric then we went out again and it didn't work. Gas side worked just fine which is what I ran it on that trip because I didn't feel like messing with it. When I got back home I pulled the Command Center control panel (old style) and checked the connections on the back of the toggle switch and blew out a bunch of sawdust and construction debris. Put the panel back in and the electric side worked fine. We've been out a couple more times and no problems. I attribute it to bad connections on the back of the toggle switch or debris on the back of the panel.

[ncitro]

Thank you for the replies!

So far I confirmed 12V at the white wire on the board when the electric switch is on. I will continue with Colan's steps over the holidays when I have more time and we're not staying in the RV. For now the water heater with works fine with LP - I just don't like 'wasting' propane when at full hookup sites.

Just for what its worth, I have done a fair amount of troubleshooting on two of these, mine and my father in law have the same one. Both had boards fail in the first two years, and mine also had the 120V relay fail. The element usually will last forever as long as you only turn it on with water in it. The board is accessible from the outside, the relay is behind the cover on the inside.

I now carry a board and a relay with me in the rig.