Water Heater noise and odd wiring

[Bierp]

Picked up our new coach last week. 2017, first owner, brand new, all that good stuff.

Today, as I was testing things before our first trip it came to my attention that the water heater was making a whining sound. I didn't notice this during the walkthrough at the dealer.

Now, before I fired it up I hit the pressure relief valve to be absolutely sure the tank had water. That, naturally, got the panel a bit wet. This should be fine, BUT, when I started poking around to find the source of the noise, it appeared to be coming from a strange wiring quirk.



The right brown wire has a strange setup. It looks like maybe there's an in-line fuse or something? It kind of looks like it's wrapped to keep it dry, but instead it's capturing water.

Now, I'm no electrician, but that can't be good.

I've been looking at the schematic and the two brown wires seem to go to the Thermal cut-off and the fixed temp cont t-stat. It looks like a circuit, but again, I'm no electrician.

The line art manual images make it look like that brown should go right into the panel without any kind of add-on.

So what is this thing, why is it there and why is it making a noise?

Details: Atwood GC6AA - 10E. Gas and Electric heat. The sound occurs with either method of heating.

Any input on this would be appreciated.


Thanks,
Bierp

[haddy1]

FWIW, if you ever need to replace that thermal breaker, make sure that it is oriented the same as your picture. If it's not installed "away" from the burner, it will blow unnecessarily.

[Lantley]

garyemunson wrote:
It is a thermal fuse, not a thermistor. A thermistor is a component that varies it's resistance with heat. They are used in modern thermostats to sense temperature. Thermal fuses just open when their cutoff temperature is exceeded and require replacement.

I agree I used the wrong term.
I stand corrected.

[Old-Biscuit]

Listen closely to area of circuit board....whiny

The 'thermal fuse' is a one time device that trips at 190*F if a flame blow-back should occur.
It is 1st in line.......when tripped it stops ALL DC Voltage shutting down WH

AS you can see......it's position is 'Normal'

[cyntdon2010]

My water heater has always made the whining sound. I just turn it off after the water heats up.

[dougrainer]

Chris Bryant wrote:
The noise is coming from the circuit board, and is normal. Yes- that is a thermal fuse.

The noise is the Circuit board. You notice that whining sound ONLY when heating on 120, since there is no noise. When your LP flame is ON, you cannot hear that whining noise due to the flame roar. This is ONLY on Atwood Water Heaters. Doug

[Chris_Bryant]

The noise is coming from the circuit board, and is normal. Yes- that is a thermal fuse.

[garyemunson]

It is a thermal fuse, not a thermistor. A thermistor is a component that varies it's resistance with heat. They are used in modern thermostats to sense temperature. Thermal fuses just open when their cutoff temperature is exceeded and require replacement.

[Lantley]

Yes that is a thermistor . It is designed to trip based on heat. If there were a fire or flames it is designed to trip the circuit, similar to a fuse but it detects heat not current. They are notorious for acting goofy and creating a poor connection. I imagine the RV industry does not use the highest quality thermistor.
As test You could just take it out of the circuit and see how things work with out it.
The circuit will work just fine without it. replace it if it is defective.

[garyemunson]

I believe that is a one-time thermal fuse. The noise is probably frying water if that is actually where it is coming from. The insulating sleeve is to keep it from shorting out against something. The body of the fuses are metal and at line potential. Kind of dangerous if left bare. It should not be in the position it is where water can get trapped in it (even from condensation). I suggest you use a razor blade to make some small slices in the tubing so moisture can easily evaporate and/or cannot get trapped. You might also want to bend the fuse wiring up so the fuse is above the two ends of the tubing. A whining noise could also just be noise of water sizzling against the heating element in the tank. Home water heaters can also do that but their bigger size makes the noise harder to hear unless you put your ear up against it. You said the noise occurs with both forms of heating.. are you sure the electric side is off when the gas is heating the water? Both can be on at the same time if you are hooked to shore power (heats water faster). For test purposes, you could remove the fuse from the circuit (it looks like it's a plug and play set up) and plug the brown wire right to the terminal and see if things are quiet. Put it back, though!