Help replacing old Atwood Water Heater with New Atwood

Old-Biscuit wrote:
NO you do not want to tie the white and orange together.

Yes...you can turn both electric and propane on at same time for faster recovery.
ANY water heater with both electric/propane can do this.

Yes......this water heater is a replacement for your old water heater in that it is a combo (electric/gas) and will fit in same opening.
But it does require new wiring scheme due to design changes.


120V AC needs to be wired to/thru the box with relay. Relay is DC activated which allows AC to element when a 12V DC ON/OFF Switch for electric is turned ON

Propane uses 12 DC and will light off when a separate 12V DC ON/OFF switch is turned ON

BOTH electric and propane use 12V DC to/thru circuit board in order to function.

You could just wire propane circuit....all wiring is already there.
And deal with electric wiring when you have proper time to do it correctly.

Am I missing something?

The instructions for the new hot water heater (figure 10 single switch hookup) says that the orange and white wire goes to the same terminal>

NO you do not want to tie the white and orange together.

Yes...you can turn both electric and propane on at same time for faster recovery.
ANY water heater with both electric/propane can do this.

Yes......this water heater is a replacement for your old water heater in that it is a combo (electric/gas) and will fit in same opening.
But it does require new wiring scheme due to design changes.


120V AC needs to be wired to/thru the box with relay. Relay is DC activated which allows AC to element when a 12V DC ON/OFF Switch for electric is turned ON

Propane uses 12 DC and will light off when a separate 12V DC ON/OFF switch is turned ON

BOTH electric and propane use 12V DC to/thru circuit board in order to function.

You could just wire propane circuit....all wiring is already there.
And deal with electric wiring when you have proper time to do it correctly.

Old-Biscuit wrote:
Your problem(s) are that you have a 1997 model WH and trying to replace it with a 2014 model.

They are NOT the same.
Atwood changed designs in 2004.

Previous used 120V AC directly to electric element via On/Off switch and set of t-stats on backside of WH tank.

The design change uses 12V DC for electric & propane operation via relay, a circuit board and 1 set of t-stats for both heat sources.

You will need a DC fused wire to a new ON/OFF switch (Dual switch with fault light is better change out than 2 separate switches)

Then that electric On/Off (White wire) thru circuit board will power a relay that is in electric cover on back of WH tank where element is. Relay triggers 120V AC to element

Propane is from DC fused wire to On/Off switch then thru circuit board (orange wire).

Blue wire is DC from circuit board to Fault Light in On/Off panel

Green is 12V DC (-)


New Dual On/Off Switch
New DC wire run for electric (white)


Old 120V AC wire to element
Old Brown wire for propane (orange)
Old Blue wire for Fault Light

Ok, so if I tie the orange and white together, and retain the old 110 volt wall switch switch....when the 110 volt wall switch is off even though the 12 volt relay has turned the 110 on, on the heater the heater will still only run on propane because there is no 110 supplied to the heater (wall switch is off).

If I turn the 110 wall switch on then the heater will run on both propane and electric for quick heat up (instruction manual says this is ok, circled in red)



The only down side is I cannot operate the water heater in just the electric mode with out adding a second switch. I cannot think of a time when I would want to do that, but my rewire in the further to be able to do that. I am currently in a time crunch as I am leaving for Norwalk this Wednesday and need to be done by then.

When I placed the order with American Coach they assured me that there were no retro fits necessary to install the heater.

There is this change to the electrical system.

The box that holds the relay for the electric operation which is on the back side of the heater is directly in the path of the plumbing (I have a solution and will post it when complete).

The tank is now insulated with foam rather than fiberglass mat which sticks out further and obstructs the outlet pipe. A little grinding to dimple the foam solved this problem.

Tom N wrote:
Have you thought about going to a new instantaneous on demand tankless water heater?? That's what I would do.

Did not want to change all the wiring and plumbing. Looks like I will have to change some wiring, and with the ridge insulation on the new unit the plumbing does not fit.

I think I will grind the insulation so the plumbing does fit.

I did go to home depot and get fitting to space it out, but that would put a strain on the piping. So the insulation will get removed, and than I will pack fiberglass insulation back in. That is what is on the original.

Your problem(s) are that you have a 1997 model WH and trying to replace it with a 2014 model.

They are NOT the same.
Atwood changed designs in 2004.

Previous used 120V AC directly to electric element via On/Off switch and set of t-stats on backside of WH tank.

The design change uses 12V DC for electric & propane operation via relay, a circuit board and 1 set of t-stats for both heat sources.

You will need a DC fused wire to a new ON/OFF switch (Dual switch with fault light is better change out than 2 separate switches)

Then that electric On/Off (White wire) thru circuit board will power a relay that is in electric cover on back of WH tank where element is. Relay triggers 120V AC to element

Propane is from DC fused wire to On/Off switch then thru circuit board (orange wire).

Blue wire is DC from circuit board to Fault Light in On/Off panel

Green is 12V DC (-)


New Dual On/Off Switch
New DC wire run for electric (white)


Old 120V AC wire to element
Old Brown wire for propane (orange)
Old Blue wire for Fault Light

Have you thought about going to a new instantaneous on demand tankless water heater?? That's what I would do.