Water Heater Works on Gas But Not Electric

[GusinCA-JAY]

Dometic GC10A-4E
Works fine on Propane, but not electric. Checked circuit breaker, looked for loose wires.
I've been told it can't be the thermostat because then the gas wouldn't work. Same thing for the circuit board controller, same thing for the thermocouple. Any ideas?
Glad propane works or my wife would kill me...

 

[JimD]

What model water heater do you have? Problem could be an open electric heating element or the relay that controls it. If it is an Atwood/Dometic water heater then most of what you stated is true. If it is a Suburban then some of the things you stated aren't accurate.

I have attached the wiring diagram for the Atwood/Dometic.

 

[kirkelli]

 

[Kevin Cooper]

Dometic GC10A-4E
Works fine on Propane, but not electric. Checked circuit breaker, looked for loose wires.
I've been told it can't be the thermostat because then the gas wouldn't work. Same thing for the circuit board controller, same thing for the thermocouple. Any ideas?
Glad propane works or my wife would kill me...

Have you verified 120 volts from board larger wires that go to the heating element? Then 120 volts to and out of the button on the stack? And if that is all good, have you put ohm meter to the heating element to verify it is not burned out?

 

[GusinCA-JAY]

It's a Dometic and I don't have a volt meter or the skills to do all of those tests, but thank you all for your help! I was hoping it might be something obvious or simple based on it only working with propane...

 

[TCNashville]

When you try the electric switch does it light up? If not it could just be the switch.

 

[GusinCA-JAY]

When I turn on the "Electric Water Heater" in the computer control panel it lights up, but the water doesn't get hot. But when I turn on "Gas Water Heater" it fires right up. I'm guessing it's either a bad control board or a bad heating element. Watching that video made me think it can be the small fuse or the ECO or TC switches...

 

[gunafulltime]

We have a Dometic water heater. Our heater did this a year ago. It was the thermal cutoff switch. It's a heat fuse. It is very easy to replace.

 

[GusinCA-JAY]

Thanks, let me take a look at that, but wouldn't that prevent the gas part from working as well?

 

[CAG-JAY]

If the electric is turned on and the water heater is empty it takes about a second and a half for the element to blow.

 

[GusinCA-JAY]

The water heater was never empty for sure (we have been hooked up the whole time). Is this the little wire inside the clear plastic or the round silver thing behind the felt piece?

 

[stinger608]

The water heater was never empty for sure (we have been hooked up the whole time). Is this the little wire inside the clear plastic or the round silver thing behind the felt piece?

If you're talking about the thermal cut off, it's the one in the clear plastic cover.

 

[JimD]

We have a Dometic water heater. Our heater did this a year ago. It was the thermal cutoff switch. It's a heat fuse. It is very easy to replace.

The thermal cutoff switch is in a control loop to the board along with the thermostat. It affects both gas and electric. My son's unit blew the thermal cutoff and it killed both sides.

 

[JimD]

It's a Dometic and I don't have a volt meter or the skills to do all of those tests, but thank you all for your help! I was hoping it might be something obvious or simple based on it only working with propane...

I believe you could acquire the skills to use a voltmeter if you just gave it a shot. I have attached some documentation that will show you how easy they are to use. You can get a really inexpensive one ($10-$20) and it will do everything you need. There will be a time in the future where a voltmeter may save your bucket. Give it a try.

 

[GusinCA-JAY]

Hahhaa! That is great. I will go buy one tomorrow!

 

[GusinCA-JAY]

The thermal cutoff switch is in a control loop to the board along with the thermostat. It affects both gas and electric. My son's unit blew the thermal cutoff and it killed both sides.

So am I understanding correctly that it CANNOT be the thermal cutoff if the gas side is still working?

 

[TCNashville]

So am I understanding correctly that it CANNOT be the thermal cutoff if the gas side is still working?

Correct. The thermal cutoff is a fusible link that if broken renders the heater unable to operate on either modes. It's a safety feature.

 

[gunafulltime]

You guys are right. I had the wrong trailer and incident in mind when I wrote earlier. The thermal cutoff was the problem on our current unit; the whole thing died, gas and electric. On our previous trailer, only the gas worked. The element for the electric was bad.
Sorry for the confusion.

 

[kirkelli]

If the electric is turned on and the water heater is empty it takes about a second and a half for the element to blow.

Actually, more like 15 second, Yes it does go quick.

 

[GusinCA-JAY]

You guys are right. I had the wrong trailer and incident in mind when I wrote earlier. The thermal cutoff was the problem on our current unit; the whole thing died, gas and electric. On our previous trailer, only the gas worked. The element for the electric was bad.
Sorry for the confusion.

Ok, thanks for the clarification. I was thinking about that. Now I just need to figure out what, on the AC110V and/or DC12V side, is going wrong...