Atwood 10 Gallon Water Heater Replacement 3E to 4E Wiring Question

[vetman90]

Hi everybody. This question is directed at anyone that has replaced their older model 3E Atwood 10 gallon water heater with the new replacement model 4E.

I have a 2002 Winnebago 35U that has a main status panel and control board in the hallway which has the hot water heater propane power switch on it with the green pilot light indicator.

The 12 volt circuit breaker panel is in the upper galley cabinet above the microwave oven. In this cabinet next to the circuit breakers is a brown typical on/off wall switch with a brown switch plate cover and it's titled "Water Heater".

If you have this layout or similar and you changed out your 3E water heater to a 4E water heater please help me with my question.

I have searched the forums and general internet sites for an answer but there isn't anything offered that is straightforward.

The original water heater has 3 12v wires, blue, green and brown on a quick connect wire plug.

The new water heater has 4 12v wires with no plug, just 4 loose wires, blue, green, white and orange.

OK so the blues and greens match up.

Which new wire goes to the old original brown wire? White or orange?

Where should the remaining 4th wire go? (it's going to be either white or orange).

My goal is to use my existing switches in the coach and NOT USE the new switch panel that comes with the water heater.

Is this even possible?

Considering there is no way to run new wiring inside existing walls, I can't simply place the new switch on the galley wall near the sink.

And I hate having abandoned switches (2 of them) inside the coach.

Because this system is both 110v and 12v I do not want to start guessing what goes where and end up ruining a brand new circuit board on the water heater.

I know anyone out there that has been here and done this will know exactly what I'm asking for here.

Thanks in advance !!!!!

[AFChap]

A tech wired mine so I can't say what color went where, but we used the existing switches. You have extra wires because of the 4e being switched on 12v circuit rather than on the 120v circuit. The new switched 12v line on mine was wired to the original wires for an electric bypass valve that was removed under warranty. That left the oem 120v switch still working, and a hidden 12v switch in the washer/dryer closet where the bypass valve was controlled. We just leave that hidden 12v switch on all the time. All you need is 12v from somewhere & you can wire around that new 12v switch.

[cbeierl]

This earlier thread may help: New water heater wiring

[shiggs68]

On your previous 3e water heater, the propane side was controlled by the brown, green, and blue wires. Blue being the DSI indicator light, green being ground and white or brown being the 12vdc on signal from the switch. The brown or white depend on the location of the thermostat/Eco, front or rear. The electric was controlled by your cabinet switch and wired to the back of the heater.

On the 4e model, you have white, orange, green and blue. Blue is still the DSI, green is still ground. The difference is white is a 12vdc signal for electric and orange is a 12vdc signal for propane. A relay is builtin to control the electric side. You do not need the previous cabinet switch.

To use your existing switches, connect the orange wire to a always on 12vdv point and your cabinet switch will control the 120vac going to the builtin relay.

Here is the service manual, see pages 24 and 25 for the wiring diagrams.
http://manuals.adventurerv.net/Atwoo...er-Service.pdf


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[shiggs68]

Any update? What did you determine?


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[vetman90]

Tomorrow I'll be able to work on the motorhome and I'll definitely update how this goes !!

Then I have an awesome motorhome horror story to share with everyone that may be hilarious for everybody that has bought a used motorhome and got in over their head with problems.

[vetman90]

I'm still lost on this wiring. I wired blue to blue, green to green and then white to the original brown wire on the plug. Turn on the switch on my main monitor/control panel and the water heater comes online with 120v.

turn off this same switch and 120v is off.

Connect the orange wire to a constant 12 volt source and the gas comes on and the water heater fires up fine.

Problem: Now there is no switch to turn off the gas operation. To me this means once the water heater needs to reheat the tank, the gas fires up automatically as the primary heat source. The electric element will only come on if I have the old original 12v monitor panel switch on. If I turn on this original monitor panel switch I now have both electric and gas heating the water. I still can't shut down gas without another switch in the constant 12v. source wire right?

If I leave the 120v power switch on then both gas and electric will heat the tank.

This is where I get lost.

I have 2 old switches to work with inside the coach. I had hoped the brown one would control 120v and the monitor panel rocker type switch would control the gas because this switch also includes the pilot on light and the pilot out light.

If I have to add a switch inline of the 12volt power to the orange wire then I'm back to not having a route from the water heater compartment to the inside of the coach.

If I can't salvage the correct functions of my 12v gas switch with the pilot light status lights then I might as well just wire up the new switch Atwood included with the new water heater and it will be in the compartment next to the water heater which is the water control board and water pump compartment as well as a large storage area.

Do I really have to go out there every time I want to switch between gas and electric??

What is Atwood thinking when they sell this new water heater with different wiring requirements and not simply including a diagram on how to wire a 4E into the old 3E system????

I have had 4 different manufacturer motorhomes but all 4 had the brown 120v. switch and the rocker style switch with the pilot on/pilot out lights.

Though these switches were located in different spots depending on the builder they were all wired the same essentially.

So Atwood gives me a dual switch with a lamp between the switches for electric on/off and gas on/off. How does the installer run wiring from the water heater to the control panel location to utilize this new switch?


I understand that my existing brown switch probably still shuts off 120v. to the water heater because I'm using the original 120v romex power supply line to the water heater.

Is there a way to restore usage of my monitor panel switch to turn gas on and off and also have the switches pilot on and pilot off lights work again as they should?

[movin-on]

I'll see if I can help you out as I did this on my 02 Horizon but it's been a while....I wanted to use the original switches as much as possible...

Green to green...blue to blue....brown to orange on 4e....You have to wire the white wire to a 12v switch from the battery...So for that switch come from the positive side of the battery (house battery) then to the new switch then to the white wire...This is for the 12v relay that supplies the 120v to the heater...

That relay is the only difference in the old and new heater...I put this switch in the cabinet under the bathroom sink.... So for 120v I turn on the original 120 v switch and the new 12v switch that I installed...Gas works with the original switch when wired this way...I did not use the combo switch that came with the new heater...Hope this helps...

[movin-on]

Forgot to mention to wire the 120v wiring fro the 3E to the relay on the 4E...

[shiggs68]

On the new 4e the orange controls the gas
and the white controls the electric heater.

With that said, forget the original 3e colors. You should have a wire that is switched 12vdc from your panel switch. Connect it to the orange.

Connect the white to a constant +12vdc which will enable the 120vac heater. However, your 120vac should be coming from the original switch in your cabinet. That switch should now turn off the electric side.

Green goes to the original green.

The 4e blue should go to the previous wire that goes to the DSI indicator lamp in your panel.


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[vetman90]

shiggs68,

Changed the wiring to match as you last advised and bingo, both my existing switches work again.

I can't thank you enough for your help with this !!

I included a 15 amp fuse inline for this wire direct from a house battery. Not sure if it should be a lesser amp fuse but at least 15 amp will definitely burn should any shorting out occur.

I realized as I installed this wire that it will keep the relay for the 110v. side of the water heater live continuously. This would place a constant draw of voltage from the house batteries (probably not very much load?).

If I were to store the motorhome for a long time and use the house battery disconnect switch I believe my hot wire to the water heater would continue to pull voltage until the batteries died right?

I'm thinking it would be worth while to add an inline switch on my water control board where all the diverter valves and the water pump is located (right next to the water heater and only separated by a removeable partition wall) so as to prevent draining the batteries over time.

I would just add this step (shutting this switch off) to my list of items to be performed for long term storage.

[vetman90]

OK got it.

Here is what I ended up with:

Blue wire to blue wire.

Green wire to green wire.

Orange wire to brown wire.

New 12v. wire from the house battery to the white wire.

Results:

The original brown wall switch turns the water heater on with 110v. electric only.

The original low voltage switch on the monitor panel turns the water heater on with LP only.

To provide both LP & electric turn both switches on.


I have no idea why Atwood can't outline this procedure and include it with these new 4E water heaters for those of us replacing an old model 3E and would like to keep using the original switches inside the coach.

Note:

Where you connect your 12v. wire powering up the new heaters' white wire is up to you. It has to be a full time on source which is actually keeping your new 110v. relay at the rear end of your new water heater "live". Keep in mind if you grab the 12v. off a house battery and you store your rig for a spell with no connection to power, this 12v. wire to the relay will eventually draw your batteries down.

For my needs, I didn't want to start poking my wiring harnesses near the water heater compartment to find a 12v. source that would always remain hot. Because my battery box in under my entry stairs right next to the water heater I opted to take my power directly off one house battery and I added an inline fuse just to be safe and added a switch next to the water heater that shuts off this 12.v source to the heaters' white wire should I store the motorhome for a while. Just as I would use my battery disconnect switch when storing the motorhome I have one more checklist item............turn off the water heater switch in the basement.

[shiggs68]

Just a quick note, you should find a constant 12vdc source downstream of your battery cutoff. In doing that, you eliminate the extra switch and if you ever sell, the buyer does not have anything special to understand.

It was also very wise to fuse that line. Remember that the fuse should be close to the source.


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[mrees72]

Thanks to you guys in this thread. I have a 2000 Allegro Bus. I had the same wiring dilemma with a new Atwood water heater. Found your discussion and followed your instructions. They were spot on. My water heater fired right up. My wiring path was a bit challenging as I too came from a house battery but I got it done.

Thanks again

Mike
Prospect, Oh