replacing Atwood water tank with dual use water tank.

[benneufeld]

hello I am planning to replace my entire Atwood G6A-7E hot water tank with another similar one. and the model of that one is GC6AA-8E. basically my first atwood model is strictly a gas only model.
And the new one is a gas and electric model as well. my motorhome is a 1994 fleetwood bounder, so i’m assuming the electrical hookup has not been done for me already. i’m really quite new to this rv diy stuff although i have plenty of carpenter and handy man experience.
so if anyone has had a history with adding in a 120 electrical hookup to an atwood water heater please give me any advice. if you can provide photos on what you did that would be so helpful so i don’t get lost on what to do, thanks again i appreciate any help anyone offers and i’m so thankful for this forum i would not be any good with these repairs without all the help, much appreciated!

I do also currently have an electric converter setup in my motorhome. so i believe that can be helpful. i will post a photo of it for you below.

 

[CharlesinGA]

The 120v is connected to the pigtails on the inboard side of the water heater tank at the bottom, inside the black cover is a relay. Black Romex goes to the relay, Relay has a black pigtail to the heater element, the white romex connects to a white pigtail that is directly connected to the other terminal of the heat element. The ground in the Romex is grounded to the tank and the relay has a 12v ground wire that also connects to the tank. The relay is controlled by a lone yellow wire that comes over the top of the tank (sometimes found inside the insulation) from the control board.

You would use a DUAL SWITCH PANEL with a fault light in between the switches to control the heater. Take a 12v hot and ground to the control panel. The hot splits to both switches. From the GAS switches an ORANGE wire goes to the water heater's orange. From the ELECTRIC switch a WHITE wire (its 12v + however, not ground) goes to the white on the water heater. From the FAULT light a BLUE wire goes to the blue wire on the water heater, and from the other terminal of the fault light where you connected the ground, you split off another ground wire, GREEN, to connect to the green wire on the water heater.

Dual spade adapters make it easy to run a power wire to a switch and also jumper that power to the other switch. Same for the ground, add a dual spade connector and run a ground to the adapter and another wire to the water heater. You can find these on the electric terminal boards at auto parts places also.

See page 25 of THIS manual for the wiring diagram for a combination electric/gas electronic water heater.

Charles

if you are going to be running new wires, go to the auto parts places and buy 25 ft rolls of 16 gauge primary wire in green, orange, blue and white, so as to keep the colors consistent. I used a MOLEX connector to connect my water heater's wires to the trailer harness which had different colors. EEK!!!!

In my case, the water heater switches are mounted in the stove hood, so it looks different but works the same.

 

[John From Detroit]

Basically 12 ga Romex from a dedicated breaker to the juntion box on the unit for 120 volt.
But you will need some changes on the 12 volt side of life as well.... The dual (Gas/electric) use 12 volt wires to control the unit. Turn it on/off and select gas/electric/both and to indicate fault.
That's a least 3 wires to/from the water heater and control panel plus 12 volt and ground (4 wires total both places) So you will need to deliver 12 volts + and - to the water heater and a 4 wire connector line to the control panel as well.

 

[benneufeld]

so i have to buy a new breaker? or can i just use a fuse?

I also believe my control panel is on the other side of the rv so i need to wire the water to that? or will i need to go to an inverter first to change the 12v into 120 volt?

 

[CharlesinGA]

Basically 12 ga Romex from a dedicated breaker to the juntion box on the unit for 120 volt.
But you will need some changes on the 12 volt side of life as well.... The dual (Gas/electric) use 12 volt wires to control the unit. Turn it on/off and select gas/electric/both and to indicate fault.
That's a least 3 wires to/from the water heater and control panel plus 12 volt and ground (4 wires total both places) So you will need to deliver 12 volts + and - to the water heater and a 4 wire connector line to the control panel as well.

You do not deliver 12v+ directly to the water heater, you only deliver the 12v+ from your fuse panel to the switches, they direct it to the water heater. Four wires, including a ground, a wire from the water heater to the fault light and one wire each for electric and gas sending switched 12v+ to the water heater electronic control. Thats all.

14 gauge Romex is usually used, the element will not draw but about 11 amps, no need for 12 gauge, hard to work with. Attachment is showing what my Atwood water heater is drawing (measuring at the load shed control box) 11.7 amps.

Charles

 

[CharlesinGA]

So the OP has an electronic version of the water heater already. So you have one switch for gas, and a fault light already? That means you only need to add one switch, or replace the whole switch panel for looks, your choice, and run one additional wire (16 gauge primary wire) for the 12v control of the electric heat. In addition you need to run the 14 gauge Romex from your circuit breaker panel to the back side of the water heater.

The intellipower unit you show in the second pic takes 120v AC and makes 12v DC to charge the battery and operate your 12v devices.

We need pics of the existing control panel, and your circuit breaker and fuse panel.

Charles

 

[CharlesinGA]

THIS Atwood service manual has your existing wiring on page 24. They show Brown for the 12v going to the heater for control of the gas heat. this brown will connect at the water heater, to the ORANGE wire from the WH. Apparently Atwood decided to change up the colors when going to the combination gas/elec WH units. This explains why, on my trailer I have a brown wire for control of the gas, as my trailer was equipped at the last minute with a combo water heater, from the factory. They wired it for gas only and then had to add a switch to control the electric heat.

This pic is the relay and junction on the heat element side of the water heater, showing the element, relay and wires entering. The Romex, due to its stiffness is wire nutted to stranded, flexible wire that has spade or ring terminals to connect to the element and relay.

Here is a colorized version of the wiring diagram for your NEW WH.

I borrowed both pics from a discussion on iRV2, pics posted by Old-Biscuit.

Charles

 

[Gary RV_Wizard]

so i have to buy a new breaker? or can i just use a fuse?

You need to provide a new 120vac circuit to feed power to the electric heat element. The heater requires 1400 watts (12 amps @ 120v), so it's a new, dedicated, 15A circuit breaker in the load center and a new 12 or 14 gauge wire to the heater. Actually 3 wires, a hot (black), neutral (white) and ground (green or bare). 14/2 with ground Romex would be the simplest. Your converter and the associated fuse panel are for 12vdc power cannot power the heater element (but they are used to power the switching).

 

[benneufeld]

so this is the back of the water heater,
all three blue green and orange wires should be wired into a pigtail that can be connected to a switch which is a variation of this.



i don’t know what a load center is? is that another circuit breaker added to my fuse breaker panel? and how does one successfully wire that in? the new dedicated 15amp circuit breaker i assume can’t just be a fuse connected to the wire coming off the relay switch right? it needs to be wired to my breaker box?

 

[benneufeld]

my motorhome also does not currently have an inverter but i will be installing one shortly in the compartment immediately next to my battery bank. i assume the 120 volt 12a at 120v won’t work untill i have hooked up my inverter.

But when i do hook up the inverter will i need to to wire the relay to it directly? or by wiring the relay to the breaker box will that go to my battery which is wired to inverter?

Thanks for all the help. once again

 

[benneufeld]

here is a photo of the back of water heater. i labeled it for what i’m understanding so far.

 

[Kirk]

hello I am planning to replace my entire Atwood G6A-7E hot water tank with another similar one. and the model of that one is GC6AA-8E. basically my first atwood model is strictly a gas only model.

Just for information purposes, you may find this helpful.

Your new water heater should have come with an installation manual but if it didn't the one here can be downloaded.

 

[Kirk]

so i have to buy a new breaker? or can i just use a fuse?

The fuses you see are for 12V. You must use a proper, 120V circuit breaker.

i don’t know what a load center is? is that another circuit breaker added to my fuse breaker panel? and how does one successfully wire that in?

The load center with where you will see the existing circuit breakers for 120V. I am thinking that you need to get help from someone with electrical experience. It probably looks similar to this one.

my motorhome also does not currently have an inverter but i will be installing one shortly in the compartment immediately next to my battery bank. i assume the 120 volt 12a at 120v won’t work untill i have hooked up my inverte

The inverter has noting to do with this project. It uses power from the batteries to make 120V alternating current from the 12V direct current from your batteries. To supply 10A of 120V alternating current will require slightly more than 100A of current from your 12V batteries. You probably do not have enough battery to do that.

. i labeled it for what i’m understanding so far.

So are you installing a used water heater that you found somewhere? If so, download the installation instructions and study them before you begin.

 

[CharlesinGA]

OK, Backing up some. Do you have the motor home connected to shore power now?

Show us a pic of the fuse panel/circuit breaker panel with the door opened.

Charles

 

[benneufeld]

hi everyone thanks so much for the help,
here is my circuit breaker panel.

 

[benneufeld]

this is also on the backside of the circuit panel door.

 

[benneufeld]

OK, Backing up some. Do you have the motor home connected to shore power now?

Show us a pic of the fuse panel/circuit breaker panel with the door opened.

Charles

hi no i don’t have it connected to shore power. just a battery.

 

[John From Detroit]

Note that if you already have a 12 volt switch inside the RV to control the water heater The needed additional wire for the "Electric" mode may already be in place... The manual will assist in identifying it. The key word in this post is "May" (Implied. or may not).

 

[Tulecreeper]

Your "load center" is your breaker box/fuse panel. Every circuit that requires 120 volts (microwave) will have a breaker; every circuit that only requires 12 volts (lights) will simply require a fuse.

 

[benneufeld]

hello so a quick update on the wiring of the motorhome. the guy i bought it from said the first owner did some upgrades but he didn’t remember exactly what he did but apparently there was some wiring done. with that being said upon further investigation into the circuit breaker and wiring setup i see the motorhome has a switch labelled water heater. and then what looks to be a 120v wire fed behind my kitchen counter for the possibility of an electrical water heater in the future.

But maybe i am just reaching, and hoping the job was done for me. if anyone can tell by the photos below this would save me so much hassle, thanks.