Operating Water Heater from AC power.

[CamJam1]

Water heater on my Dolphin has never worked on AC since I bought the rig 2-1/2 years ago. Not a big issue as it works fine on propane, but I'm wondering if it's defective or maybe this was an option that I don't have. The power switch doesn't light up when I flip it on like the propane switch does. Is there something on the water heater itself that would tell me whether mine has AC capability?

[Old-Biscuit]

Check the Model in the outside compartment
GC10A-4E would be a Gas/Electric Combo
G10A-4E would be Gas only

Atwood water heater....2004 1st year of new version that uses 12VDC to operate/control both gas/electric

Same DC power, Same set of t-stats, same circuit board so if propane works them issue is limited to DC Voltage to DC Relay which when closed allows 120VAC to Element

DC Relay and Element are on BACKSIDE of water heater tank under protective cover
Yellow wire from circuit board (in outside compartment) sends the DC to Relay.
*with water cold...turn AC switch on and check for 12VDC on the Yellow wire
Got DC Voltage...then problem is with DC Relay or 120VAC to/from relay (melted wiring/terminals) or with AC Element (burnt out/shorted)

To isolate need to access backside of WH Tank...remove cover and inspect/test Relay/Element
*Not always easy on a MH...sometimes the WH has to be removed from RV

[John Boy]

I got tired of replacing the relay that was original. Went to an electoral supply store and got a much better one. No trouble for over a year. Take your old one with you to be sure the replacement is equal or better than the original. It may not fit back in the cover. Add a "handy box" if you want to cover it.

[John Boy]

Electrical not electoral.

[Belgian]

Have you tried leaving the 120VAC switch on for a while to see if the water gets hot? The reason I ask is my switch has a bad LED light inside the switch, but the heater works fine.

[hydro45640]

When I I purchased my Motor home the hot water would not heat on electric.
I discovered that on the back side of the heater there is a rocker switch that turns on the AC heater. Check to see if yours has that switch.

[CamJam1]

Great tips everyone, THANK YOU! I'll check these things out.

[Old-Biscuit]

Originally Posted by hydro45640

When I I purchased my Motor home the hot water would not heat on electric.
I discovered that on the back side of the heater there is a rocker switch that turns on the AC heater. Check to see if yours has that switch.

Up thru the 2003 Model Version....Yes the 120VAC on/off switch was on backside along with AC set of t-stats and element

2004 Model Version to present.....No ---AC on/off switch inside the RV


**OP is on the cusp
2004 model.......built when??
depending on build date could have last of the 2003 Model Versions
GC10A-3E

[CamJam1]

Originally Posted by Old-Biscuit

Up thru the 2003 Model Version....Yes the 120VAC on/off switch was on backside along with AC set of t-stats and element

2004 Model Version to present.....No ---AC on/off switch inside the RV


**OP is on the cusp
2004 model.......built when??
depending on build date could have last of the 2003 Model Versions
GC10A-3E

Hmmm, interesting. My chassis was built 4/2004 as I recall.

Model number of the water heater mentioned in the second post above confirms I do have the combination gas/electric water heater.

So if there is no switch on the back of WH and no switch inside, how do you switch from gas to electric? I do have an inside switch, it just doesn't seem to do anything.

Looks like to access backside of water heater I have to climb under the coach and remove an access panel.

[Richard S.]

Could just be a bad switch inside, check the wires on the back side of the switch.
Have you ever left tht switch on for any amount of time, could be that the light in the switch is burned out. When on 120 volt it is silent.

[Old-Biscuit]

Originally Posted by CamJam1

Hmmm, interesting. My chassis was built 4/2004 as I recall.

Model number of the water heater mentioned in the second post above confirms I do have the combination gas/electric water heater.

So if there is no switch on the back of WH and no switch inside, how do you switch from gas to electric?

No inside/none on backside then it is NOT a combo gas/electric Just GAS Only with inside switch


I do have an inside switch, it just doesn't seem to do anything.

Looks like to access backside of water heater I have to climb under the coach and remove an access panel.

So yours is GC10A-4E Version.....correct?

2 inside switches ...one for Gas and one for Electric....correct?

IF YES...then read my 1st post about the Yellow wire and DC Relay etc

Wiring for 4E version (and 10E 6al combo versions)

[CamJam1]

Thanks OB. Yes, mine is a GC10A-4E, and I do have inside switches for both gas and electric. I'll check out the yellow wire and relay per your earlier post.

I have previously left the AC switch on for long periods to see if it was just a burned out bulb in the switch, but the water never gets warm.

One more question: Assuming the system is working as it should, what happens if both gas and electric switches are on simultaneously?

[Richard S.]

With both switches on at the same time and working correctly, you have hot water real fast.

[CamJam1]

Originally Posted by Richard S.

With both switches on at the same time and working correctly, you have hot water real fast.

Nice! Now just need to figure out what's wrong with the AC side of mine.