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.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.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???

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

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 elementPropane 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 SwitchNew DC wire run for electric (white)Old 120V AC wire to elementOld Brown wire for propane (orange)Old Blue wire for Fault Light

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.

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 elementPropane 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 SwitchNew DC wire run for electric (white)Old 120V AC wire to elementOld Brown wire for propane (orange)Old Blue wire for Fault LightOk, 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.

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

Help replacing old Atwood Water Heater with New Atwood

getaround2it
Explorer
Sep 24, 2015
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.
Bird_Freak
Explorer II
Sep 20, 2015
Great job!
GlennLever
Explorer
Sep 20, 2015
getaround2it wrote:
GlennLever, excellent post here and exactly the topic that I was looking for. :)

What became of getting your "electric only" function resolved for your water heater?

I fulltime in my 2002 Winnebago and stay on my sons property. I don't take the motorhome out very often for the time being and I don't want to deplete my propane on hot water when I am plugged into 30 amp 120v full time. I want to keep my propane available for cooking only. I heat the coach with 120v when needed too.

So I want to use my new replacement 4E water heater on electric only. This will allow me fewer trips to have my propane tank refilled and also prevent me from having to buy into the "stay awhile" portable tank propane source should my builtin tank run empty at a time I don't want to move/drive to a refill point.

I'm parked and set up on a slope requiring lots of levelling blocks and it's not so easy to just raise the jacks and go.

I also wish to keep my existing switches functional and avoid installing the new dual switch the new water heater came with which would have to be installed on my water control panel inside the basement compartment next to the water heater compartment.

Have you found a way to separate your white and orange wires to gain the "electric only" feature by utilizing your existing indoor coach switches?

As I search the web for answers I have found one forum member on a different board that had a tech accomplish this on a similar Winnebago but the owner has no idea how the tech actually wired it. :(

So currently I have not wired my water heater yet.

Ok...

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.

So...
If you tie both wires together, turn the gas valve off, the heater should work on just electric.

Failing that, just hook up the electric wire to your single switch and the unit should only want to work of electric.
Chris_Bryant
Explorer II
Sep 20, 2015
getaround2it wrote:

What became of getting your "electric only" function resolved for your water heater?
...
Have you found a way to separate your white and orange wires to gain the "electric only" feature by utilizing your existing indoor coach switches?

Simply hook the white "electric" wire directly to a 12 volt source- you will have to find power close to the heater to avoid running an extra wire.
This is about the only way to do it, as the heater uses the single thermostat and a relay, which must be used.
getaround2it
Explorer
Sep 20, 2015
GlennLever, excellent post here and exactly the topic that I was looking for. :)

What became of getting your "electric only" function resolved for your water heater?

I fulltime in my 2002 Winnebago and stay on my sons property. I don't take the motorhome out very often for the time being and I don't want to deplete my propane on hot water when I am plugged into 30 amp 120v full time. I want to keep my propane available for cooking only. I heat the coach with 120v when needed too.

So I want to use my new replacement 4E water heater on electric only. This will allow me fewer trips to have my propane tank refilled and also prevent me from having to buy into the "stay awhile" portable tank propane source should my builtin tank run empty at a time I don't want to move/drive to a refill point.

I'm parked and set up on a slope requiring lots of levelling blocks and it's not so easy to just raise the jacks and go.

I also wish to keep my existing switches functional and avoid installing the new dual switch the new water heater came with which would have to be installed on my water control panel inside the basement compartment next to the water heater compartment.

Have you found a way to separate your white and orange wires to gain the "electric only" feature by utilizing your existing indoor coach switches?

As I search the web for answers I have found one forum member on a different board that had a tech accomplish this on a similar Winnebago but the owner has no idea how the tech actually wired it. :(

So currently I have not wired my water heater yet.
GlennLever
Explorer
Jul 22, 2015
Traveled for 5 days this past week and the water heater worked flawlessly even through heavy rain.

I did try putting the air pocket in the tank, did not change the drip.
Old-Biscuit
Explorer III
Jul 13, 2015
Due to closed system and higher normal temp t-stats weeping can occur when air gap is not present.

Air gap allows for swelling of water when heated and absorbs increase in pressure

Turn off water supply
Open faucet hotside to relieve pressure
Open T&P Relief Valve with lever,,,,,,,,,,when water stops flowing out let it snap closed
Turn on water supply close faucet
GlennLever
Explorer
Jul 13, 2015
Ok...Almost the finial chapter in the water heater install.

I left the heater on over night with the internal pump on to keep the pressure up. No Leaks!

This time I was smart and drained the tank before trying to move it.

Once drain I pulled the unit out far enough so I could apply butyl tape to the back side of the flange.

I started in the middle at the bottom and went all the way around the unit with one piece.

This was a fresh roll and working with it compared to my experience with the refrigerator was a dream.

I attempted to use the original holes but the flange holes did not line up with the holes in the motor home.

I probably could have made them work, but I drill new holes so the screws would go in straight. I replaced the original self tapping screws with stainless steel screws.

One drill to drill the holes and the other to screw the screws in.

I trimmed off the excess butyl that was squeezed out leaving about 1/8 excess still sticking out.

I used my fingers and squished the excess into a semicircle so water would not sit on the edge of the sealant.

All of this including the silicone that I could not get off that was applied by a RV Service Center is hidden behind the cover.

Speaking of the cover, there is what appears to be a view port in it. It has always bothered me that it was opaque.

Time to do something about it.

I cut it out and epoxied a small piece of Plexiglas over the hole from the inside.

I do not know what it's purpose is but now it is clear.

So when install what you see is the bolt that hold the air color on the gas valve in place.

Anyone know why this is here?

The inside hatch cover is put back in place.

Finished, right?

Well after several heating cycles the pressure relief valve has started to drip when the temperature of the water gets close to the high point. If I relieve the pressure by turning a hot water valve on the dripping stops.

My old tank used to do this. I replaced the pressure relieve valve on that unit and it still did it.

I have had a conversation with several people and they tell me this is a common problem,. That these hot water heaters heat the water hot as there is limited quantities of the hot water. That means you can mix more cold water with it and the hot water lasts longer.

Do you have this problem.

I am thinking of installing a drain hose from the valve through the coach and to the bottom of the coach just as the defrost from the refrigerator does.
Old-Biscuit
Explorer III
Jul 13, 2015
Glenn,

Heck of a change out.........most would have given up

You recognized the issues, found a solution and made it work

VERY nice write up and pictures.

I apologize for 'questioning you'...just playing 'devils advocate'.
Didn't want you to be wiring it up w/o bypassing safety controls.

Good job!!!
GlennLever
Explorer
Jul 13, 2015
Chris Bryant wrote:
I really would not leave the element exposed on the back- any connection like this needs to be in a flame resistant enclosure, and I have seen many water heaters smoke the wiring at the element, plus the possibility of someone reaching blindly through the access hole and getting shocked.
There is plenty of flex in that pipe to add a longer nipple at the tank.

The box that Atwood had over the element on the new unit was plastic, on the old unit was metal. I will cover the element with the old metal box.

I have to drain it today so I can move it to seal the outer lip and will add the box when I do that.