Water Heater Trouble

[Loopyj]

Hi there,

I have an ‘04 fifth wheel with an Atwood water heater. If not the original, it’s at least older. I’ve been running it on electric since full timing, and I replaced the pressure relief valve as the previous one was corroded to the point it wouldn’t close all the way.

A few days later, I noticed my red light was on. The light kicks on almost immediately, and I know the WH is not starting up at all. This happened before a trip, and when I came back, 4 days later, it worked fine. I woke up today to the light on again.

It gets down to about 32 at night, so I thought something must’ve froze. It’s about 60 in the day, so I figured it thawed and all was working magically again.

Any ideas on what the issue could be, and if the cold temp could be playing a factor?

Kindly,
LoopyJ

[OldandOlder]

I'm not sure I understand the situation. You state that you have been running the water heater on electric, then it seems that you indicate the gas burner fault light. Others may understand your post, but I'm old and slow. Please clarify it and I'm confident that others who are much sharper than I am will help solve your problem. There are some amazingly sharp folks on these forums. Have a great day in spite of the water heater problems.

[Loopyj]

Thank you, old and older. A good day is always needed when there’s no hot water.

My water heater is ran off of two switches (one for electric, one for gas) and the switch is inside my camper. Just like a light switch. The indicator light comes on when the electric switch is on…sometimes. It worked fine until it quit working for four days, and then I returned from a trip, and it was magically turned in with no red light. I took a hot shower, did the dishes, all was well.

Today, I’m back in the same boat where the red light turns on when the electric switch is on (not the gas switch).

[Old-Biscuit]

2004 Atwood gas/electric uses one set of T-stats and common circuit board to control both heat sources

The Fault Light triggers :
*If gas flame fails to light/prove it lit
*If ECO (Energy Cut Off---HI Temp T-stat opens

On Electric it can 'indicate open' because the Millivolt is not being sensed by circuit board ......circuit board sends a millivolt current to/thru ECO to gas valve to ground
This places the ECO in the Temp Control Loop should T-stat fail to open then the ECO opens stopping Heating cycle

Doesn't take much to stop that millivolt signal so check the Spade/Terminal connections on the ECO, check the ECO Terminals
If loose, dirty, corroded the 12VDC when on gas may be OK but the Millivolt can be interrupted hence RED Fault light and no electric heating

[Loopyj]

Thank you, old biscuit. I appreciate all the detail. I checked these terminals and everything looks fine. I need to get a multimeter to check further.

Would the likely fix then be replacing the thermostat assembly and/or the thermal cutoff? Would there be any reason the control board is at fault?

[Loopyj]

Also, I should mention that I don’t think it’s working in gas either. I’m brand new to this, and hadn’t needed to use the gas feature to this point. The igniter is loosely attached as the small bolt rusted away. Just mentioning this in case it indicates another issue.

[Old-Biscuit]

Thermal Cutoff is a one-shot fuse....blows when exposed to 190*F (flame blow back)
Has to be replaced if it blows...nothing intermittent with it, Shuts down all DC so RED Fault light would NOT have any DC

Seeing as the issue is when using the Electric (Gas works OK) then circuit board should not be the issue as the 'Power Track' is same for Gas and Electric

Could do a 'Valve Track' continuity test----you would have to disconnect everything from circuit board and remove it to test
*Continuity between Ground Edge connector and Valve Edge connector (Green to Red)
But think that would be LAST resort

I would replace the ECO/T-stat Set
Clean up Tank wall where they make contact and make sure spade connectors are clean/tight----New ECO/T-stat tight to tank wall
*2004 OEM ----17 yrs old is pretty good life span for t-stats

Atwood 91447 (ECO/T-stat Set) ---- ECO has Large terminals so you can't mix up which is which

[jl.kauai]

Loopyj Before you replace anything try one more thing. You said you checked the connections? Did you actually pull the fittings on and off a couple of times. This will clean the contacts of any corrosion usually. Sometimes the look fine but are not making good contact. Worth a try. I’m referring to the bayonet type fittings that just slip on and off where the wire attaches to the male fitting.
Travato John

[Old-Biscuit]

Originally Posted by jl.kauai

Loopyj Before you replace anything try one more thing. You said you checked the connections? Did you actually pull the fittings on and off a couple of times. This will clean the contacts of any corrosion usually. Sometimes the look fine but are not making good contact. Worth a try. I’m referring to the bayonet type fittings that just slip on and off where the wire attaches to the male fitting.
Travato John

Good point.....

I 'inferred' OP had done that.....
Pull the spade connectors off the terminals (ECO & T-stat)
Wiggle the ECO/T-stat Terminals...they should be tight/connected to the t-stat base and clean
Spade connectors on wires should be CLEAN and have good contact with the wire

I also missed his post about gas not working
Rusty bolt for spark electrode. That mounting screw provides Ground for spark electrode
Time for NEW Spark Electrode Assembly......


TRY THE GAS......post if it fires off/sparks etc

[Loopyj]

Hey all,

Sorry to keep you waiting for the results. Great news with the repair. It turns out the ground screw (the one attached to the electrode) had sheared off from rust. Simple as that. I had parts ready to swap, hoping it wasn’t needing replaced. For now, it’s running like a dandy. Thank you all for your help though. I’m more equipped and educated for the inevitable.

[Old-Biscuit]

Thanks for posting update and resolution

Much appreciated!