Atwood/Dometic water heater problem

[Corn]

I have the 6gal. model GC6AA-10E dual Electric/gas.

I am parked in a RV park where I have been through some nights in the teens and single digits lately. I have left the water running at a good stream all night to prevent freeze-up. I leave the hot & cold sides going as the first night of this I only let the cold run and the hot side froze up. My problem is that I have had to replace the thermal cut-off fuse twice after doing this, part# 93866. I am at a loss for what is causing this, or rather why leaving the hot water at a low stream all night would cause this. Any help would be greatly appreciated here!

Thanks in advance!

[A32Deuce]

What kind/type unit are we talking about? My class c,runs the heat lines with the water lines and using the propane heater keeps them from freezing. Where I am now, southern Bama, used the on board and cold water stream in teen weather over several nights and no problem.

[Corn]

GD Reflection 315RLTS TT

[A32Deuce]

That will help with someone that has your type unit since they are different. If your water lines are inside your cabinets, people leave cabinet doors open so heat can circulates in them. Not always, but just using an electric heater to save on propane turns into a costly problem. Running the hot water with out turning off the heat part causes continuous current which I don't think it was designed for. I could be wrong, but logic would seem so.

[Bshevel]

Originally Posted by Corn

I have the 6gal. model GC6AA-10E dual Electric/gas.

I am parked in a RV park where I have been through some nights in the teens and single digits lately. I have left the water running at a good stream all night to prevent freeze-up. I leave the hot & cold sides going as the first night of this I only let the cold run and the hot side froze up. My problem is that I have had to replace the thermal cut-off fuse twice after doing this, part# 93866. I am at a loss for what is causing this, or rather why leaving the hot water at a low stream all night would cause this. Any help would be greatly appreciated here!

Thanks in advance!

Here is a quote from Wikipedia that might point to the problem "Thermal fuses are usually found in heat-producing electrical appliances such as coffeemakers and hair dryers. They function as safety devices to disconnect the current to the heating element in case of a malfunction (such as a defective thermostat) that would otherwise allow the temperature to rise to dangerous levels, possibly starting a fire."Maybe the E.C.O. Thermostat might be the source of the problem.

We have a different issue with our model GC10A-4E water heater. Our electric heating has quit but our propane side is working fine. I should check the continuity on the heating element but there is one difficulty. For some insane reason the heating element is on the back side of this model. The whole unit has to be pulled to access it. Has anyone on the forum attempted this. It recommends that a factory technician should be the only one to do it.

[Corn]

Originally Posted by A32Deuce

That will help with someone that has your type unit since they are different. If your water lines are inside your cabinets, people leave cabinet doors open so heat can circulates in them. Not always, but just using an electric heater to save on propane turns into a costly problem. Running the hot water with out turning off the heat part causes continuous current which I don't think it was designed for. I could be wrong, but logic would seem so.

I think your logic is about right on its design not being to run constant current. I do know the heating element is good because replacing the thermal cutoff allows it to heat on electric. It will turn off the heat and check to see if she fires back up in the AM. I may go ahead and replace the thermostat just to cover that base as it is readily accessible.
As always, thanks for your time to post and help out!

[Old-Biscuit]

T-stats (Normal or ECO) have NOTHING to do with 'Thermal Fuse' failure

Thermal Fuse is a DC 'one shot' temp device that BLOWS at 190*F due to 'blow back' from burner or combustion chamber. Either due to high propane pressure, dirty burner or most likely obstructed combustion/exhaust chamber.
When exposed to the high flame temp it blows shutting down ALL DC from circuit board (Clear Plastic/Brown Wire). Has to be replaced when t blows


T-stat (normal temp t-stat) controls the normal heating cycles
OPENS at 140*F to stop heating-----CLOSES at 110*F to restart/allow heating cycle

ECO (Energy Cut Off---HI Temp t-stat) back up safety device to T-stat if it fails.
OPENS at 180*F to trip all heating. Triggers FAULT Light/Lock Out
CLOSES at 150*F but owner has to reset FAULT Light/Lockout for heater to function

T&P Relief Valve..last ditch safety device
OPENS at 210*F/150 PSI ----blows steam/scalding hot water out allowing cold water flow IN at max rate to cool water heater down. CAN still heat but someone should notice T&P blowing and shut down water heater power

NOT having EASY/CONVENIENT access t electric element is NOT Atwood's fault.
RV MFG decides WHERE to install and THEY are the ones that need to make provisions for access to both sides of water heater. BLAME THEM on poor installation.

MOST do make provisions for an access panel/cover...SOME do NOT and water heater has to be removed to get to backside (Stupid RV MFGs)

Both '10E' and 4E' versions are same except for tank size.
Same wiring scheme
Use same set of t-stats and DC to control both electric and propane
120V AC is triggered to element by a DC Relay
DC Relay and element under protective cover on backside
Could be bad DC to DC Relay, Bad DC Relay, Bad AC wiring on Relay, Bad wiring at Element, BAD element (Common issues are bad AC wires to/from DC Relay and burnet out element)

Simple continuity test on element or 120V AC Voltage Test

Wiring Scheme (OEM Colors)


T-stat/ECO/Thermal Fuse


Element is a screw in style...1400W
1 1/16" Socket

[Corn]

The water heater was in electric mode when this happened. I would then short across brown wires to check and make sure th a T it would ignite in gas mode and then replace the thermal cutoff that was bad both times.

[Corn]

Also can't be bad element as it heats with electric after cutoff replacement.

[Old-Biscuit]

Originally Posted by Corn

The water heater was in electric mode when this happened. I would then short across brown wires to check and make sure th a T it would ignite in gas mode and then replace the thermal cutoff that was bad both times.

Originally Posted by Corn

Also can't be bad element as it heats with electric after cutoff replacement.

Thermal Fuse is ONLY tripped due to EXCESS Heat source directly on the fuse.....electric element can NOT cause that.
ECO trips prior to high enough temp being reached which is measured on tank wall.
Thermal Fuse hangs out in the open ABOVE combustion chamber/burner.

Sounds like electric and propane were on at same time (fastest recovery) and propane flame flared back tripping thermal fuse.


Information about element replacement/testing etc was for the poster that mentioned his was not working