First Trip and no Hot Water

[Wright5]

Currently on our first trip with our 2020 31MB and I can not get either the electric or gas functions to engage on the Dometic. There is no gas flow, no clicking, no function what so ever and both lights stay red. Could it be a completely faulty circuit board? I am going to call tomorrow for a repair but want to make sure I'm not missing something first?

[Country Campers]

Welcome.

If there is no gas flow you will want to make sure the propane cylinder is on and full. To check if you have gas to the RV turn on gas and try to light a stove burner. If gas is present here then you may have a problem at the water heater. A red light for the electric side of the heater may mean that the breaker is not turned on. You can check this at the power panel. Another check is the hot water heater itself. Open the door to the heater , make sure all electric is off , and check all of the plug connections there to make sure they are all seated properly. The circuit board is only for the gas , if it is bad it should still work on electric.

Let us know what you find.

Brian

[TucsonJim]

Some water heaters have a switch on the water heater itself. And the switch is sometimes hard to see because it's hidden behind plumbing or electrical lines. Take a good look to see if you have a switch on the heater and make sure it's turned on.

Jim

[Wright5]

Welcome.

If there is no gas flow you will want to make sure the propane cylinder is on and full. To check if you have gas to the RV turn on gas and try to light a stove burner. If gas is present here then you may have a problem at the water heater. A red light for the electric side of the heater may mean that the breaker is not turned on. You can check this at the power panel. Another check is the hot water heater itself. Open the door to the heater , make sure all electric is off , and check all of the plug connections there to make sure they are all seated properly. The circuit board is only for the gas , if it is bad it should still work on electric.

Let us know what you find.

Brian

Hi Brian, thank you for the response. Yes I did had done all that you suggested prior to posting my question. This morning I'm going to uplug the power and shut off the batteries and see if it will "reset" the water heater. Otherwise I seem to be out of options I guess?

[howson]

Hi Brian, thank you for the response. Yes I did had done all that you suggested prior to posting my question. This morning I'm going to uplug the power and shut off the batteries and see if it will "reset" the water heater. Otherwise I seem to be out of options I guess?

Wright5,
If you're not 100% sure you understand what I'm writing about below--and given that this is a new unit--get the issue diagnosed and repaired by your dealer. It's very easy to make a mistake and burn up components or even hurt yourself while trying to measure voltages on live circuits.

I think you're on the right track if you're thinking the issue is in the 12V circuit. That's the only commonality I can think of between the gas-fired circuit and the 110V heating element.

I went out and looked at my water heater (my trailer is in the back yard). Here's the model in my '19 315RLTS:



The manual for it is referenced on the sticker (note highlighting in the second picture). I found the manual by googling "MPD 93756" and then looking through the returns for a Dometic link.



The wiring diagram in the manual is not incredibly helpful. One easy thing you can check--are the Gas and electric switches on the Convenience Panel lighting up when they are turned on? If they are, that means 12V is getting to them. But is the 12V getting to the water heater?

I did some more searching though and stumbled across this website (that I cannot vouch for): http://lyzontopoftheworld.com/atwood-water-heaters/

On that website is this diagram:



That looks exactly like what I see on my water heater (except the orientation of the drawing is 180 degrees off from how the board is mounted in the heater):




If you're comfortable with a multimeter and know what you're doing, it should be easy to look for 12V at the white (electric on) and/or orange? (gas on) to ground. There should also be 12V on the second green wire.

Again--I urge you to take this to your dealer for resolution since it is a new unit.

-Howard

P.S. Please let me know what fixes your problem!

[Yattr]

I just purchase a 367BHS and the fuse was bad on the circuit board. But this was minor compared to the hot AC line to the WH having been pulled out and just lying on the basement floor!

[Wright5]

I just purchase a 367BHS and the fuse was bad on the circuit board. But this was minor compared to the hot AC line to the WH having been pulled out and just lying on the basement floor!

Was it the 2 amp fuse? I am going to test them either way...thanks!

[Wright5]

Again--I urge you to take this to your dealer for resolution since it is a new unit.

Thanks so much for all your help! I had my engineer brother, who has the same water heater in his trailer, take a look at it and he is convinced it isn't hooked up in back. I'm goong to be taking it to the dealer this week and will let you know the final verdict.

[tonyr281]

I had the same issue. I called the dealer and they told me to check the thermal fuse. Yes it was bad, and ordered 4 from Amazon. Problem solved.

[howson]

tonyr281 -- the problem may very well have been a defective fuse, but usually a fuse opening is a symptom not the problem. The fuse should normally open if the water heater's temperature exceeds 180 degrees--which means the thermostat (another little gizmo on the water heater) did not open at 140 degrees like it should. Read back through this thread and (hopefully) that will make sense.

Bottom line: if the fuse continues to "blow" (open) there's another problem--please do not ignore it.