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Open Roads Forum  >  Tech Issues

 > Help replacing old Atwood Water Heater with New Atwood

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GlennLever

Rochester, New York USA

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Posted: 07/11/15 02:14pm Link  |  Quote  |  Print  |  Notify Moderator

Well I am trying to replace my old 10 gallon electric / gas Atwood water heater.

Water inlet and out let appear to be in the same location.

110 volt line hook up is in the same location.

The old unit has three wires from the control unit (Blue, Green, Brown)

The new unit has four Blue, Green, Orange, White)

It appears that the old unit used brown to trigger gas in the hot water heater, and the 110 was turned on manually either by a switch on the back of the unit or in my case a manual separate switch in the bathroom.

[image]

The new unit appears to have a separate line for gas and electric and the white (for electric) troughs a relay on the back of the unit for electric.

There appears to be a way to use the same single switch I currently have by tying the orange and white together.

The new instruction are really bad.

[image]

Has anyone run across this?

What I think I do is use the single switch and than if I also want electric I use the switch in the bathroom to supply 110 to the relay which will be thrown because the "Atwood switch is already on???


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Tom N

Sarver, PA/Crystal River, FL/Shelocta, PA

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Posted: 07/11/15 04:41pm Link  |  Quote  |  Print  |  Notify Moderator

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

[image]


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Old-Biscuit

Verde Valley

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Posted: 07/11/15 05:06pm Link  |  Quote  |  Print  |  Notify Moderator

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


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GlennLever

Rochester, New York USA

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Posted: 07/11/15 05:09pm Link  |  Quote  |  Print  |  Notify Moderator

Tom N wrote:

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

[image]


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.

GlennLever

Rochester, New York USA

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Posted: 07/11/15 07:39pm Link  |  Quote  |  Print  |  Notify Moderator

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)

[image]

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.

Old-Biscuit

Verde Valley

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Posted: 07/11/15 10:42pm Link  |  Quote  |  Print  |  Notify Moderator

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.

GlennLever

Rochester, New York USA

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Posted: 07/12/15 06:18am Link  |  Quote  |  Print  |  Notify Moderator

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>

[image]

Chris Bryant

Arden, North Carolina

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Posted: 07/12/15 06:29am Link  |  Quote  |  Print  |  Notify Moderator

You can do as you suggest- the only thing you will not be able to do is run the water heater on electric only- only gas, or gas/electric.
If it is going to be impossible to pull a new wire to the original switch, you could mount the new switch close to the water heater and feed it with the old line. Original switch would be a "master" (I would then wire the light to simply indicate "on").


-- Chris Bryant

Old-Biscuit

Verde Valley

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Posted: 07/12/15 06:42am Link  |  Quote  |  Print  |  Notify Moderator

That diagram is showing wiring for gas or electric with one switch.....

What is missing is that 2 switches are needed. One for each heating source.



Can you tie both to 1 single switch. Never tried it. Not a normal/standard configuration
Both electric/gas would operate ALL the time/at same time.
No individual heating option.
IF 'Fault' occurs don't know if both sources would trip or just one with issue ?
(Individual switches.......only the one with issue would trip on fault. Fault reset by turning On/OFF switch off then back on--after issue repaired that caused fault)

GlennLever

Rochester, New York USA

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Posted: 07/12/15 06:49am Link  |  Quote  |  Print  |  Notify Moderator

Old-Biscuit wrote:

That diagram is showing wiring for gas or electric with one switch.....

What is missing is that 2 switches are needed. One for each heating source.



Can you tie both to 1 single switch. Never tried it. Not a normal/standard configuration
Both electric/gas would operate ALL the time/at same time.
No individual heating option.
IF 'Fault' occurs don't know if both sources would trip or just one with issue ?
(Individual switches.......only the one with issue would trip on fault. Fault reset by turning On/OFF switch off then back on--after issue repaired that caused fault)


Instructions says that when operating both if the gas fails to light the fault light will not light and the unit will continue operation on just electric.

The old unit had a separate wall switch to supply 110 electric to the heater. If I use the same wire the new unit will not receive 110 unless the wall switch is turned one (even if the units relay for 110 is tripped by the single switch).

I think I'm good that way.

Now I just have to overcome the physical differences (location of the 110 relay box on the rear is in the way of the plumbing, and the ridge foam insulation on the back sticks out and interferes with the plumbing also

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