Atwood Water Heater question

[DavidTL]

Good day to one and all! I have a 40' 1997 CC Magna. The water heater is an Atwood unit. I am trying to run it on shore power rather than LP. The switch inside the galley is simply an ON/OFF type with no selection for LP or Elect. The unit fires up on LP just fine, but I have zero clue how to make it run on AC. I turned off the LP which obviously extinguished the flame, and now the RED indicator on the switch is illuminated. Any assistance on this would be GREATLY appreciated! --David

[deandec]

If your Atwood Water heater is the same as mine, it was delivered with only a propane water heater but is 10 gallon.

I bought a gizmo called the Hott Rod 15 years ago and installed it into my tank. I then installed a lighted switch in the galley cabinet and connected it to the Hott Rod. It uses 110vac to run the heater.

It is still working some 80K miles later. Looks like Amazon will sell one for about $110. 3x what I paid I think.


The manual will tell you that when the propane does not ignite in the water heater, the ignitor switch will turn red.

You need to turn it off and try again (perhaps three times).

When the rig or heater have not been used for an extended period, I ignite a burner on the stove to first confirm that the gas is flowing in the line.

[DavidTL]

Dean, Thank You for reacing out! The label on the heater states/Gas/Electric, as well as the CC owners guide which states my coach was delivered with a gas/electric unit. It even cautions NOT to turn the unit on 12VAC unless the tank is full to not harm the heating element. However, the manual DOES NOT address operation?

[deandec]

David, the switch for gas ignition is still turned to on, red, so you need to turn it off.

I missed the part where you had the propane burner working and then turned the gas off at the tank. I suspect that is why the lighted propane switch is showing red for ignition failure.

There must be a switch somewhere that turns on the electric feature. However I would not think a 12v electric current will provide much hot water.

Hopefully someone with your water heater will chime in.

My added electric feature is not 12v. It is 110vac.

[Ljwt330]

We need the model number of your heater.

The CC manual describes a gas/electric operation, but that could just be a generic description to cover all options. You need the manual for that particular heater model.

I assumed the 12vac was a typo, and you meant 120vav.

It’s possible you do have a gas only heater.

If you do have the electric option, the switch should be on the control panel with the gas switch. We can’t see where the LP switch is but the electric should be adjacent. I believe you if you say it isn’t there.

A picture of the heater switch location would help.

Look inside your 110v electrical panel. Is there a circuit breaker labeled “water heater?”

[ArtJoyce]

I have seen the electric heat switch on the water heaters three different ways. 1) on the same switch panel as the propane panel, 2) some other place normally near the propane switch. 3) inside the water heater box accessed from the outside.


But if you have the model number it would help.

[phays]

To turn on the electric water heater in my 2000 Magna I have a circuit breaker in my house electrical panel that must be turned on. There is no other accessible switch. Both propane and electric can be run at the same time.



As a note, there is another switch on the back of the water heater that must be in the on position but it is not the normal switch we would use to turn on the electric element. In my coach, the water heater is under the floor of my bedroom closet and to access the backside of the water heater where that switch is located means I have to remove the floor panels. That switch on mine failed. Also, should the water heater ever overheat there is a small reset button on a high temperature switch on the back side of the water heater that must be reset to get the electric element to work.


Also, in 2003 Atwood moved the electric controls to the front of the water heater with the propane controls. So if you have the newer water heater your electric reset button is accessed from the outside cover.

[Old-Biscuit]

Atwood Gas/Electric of your vintage would have the GAS on/off switch inside RV with a FAULT Light
The AC Electric on/off switch would be on the backside of water heater on the protective cover over the AC Set of T-stats and the Element
*AC from circuit breaker goes directly to that on/off switch


RED Fault Light should not come on when turning GAS off
It comes on when flame fails to light & PROVE it lit
Flame Sensing safety feature

Middle or bottom diagrams

[Old-Biscuit]

Originally Posted by phays

Also, in 2003 Atwood moved the electric controls to the front of the water heater with the propane controls. So if you have the newer water heater your electric reset button is accessed from the outside cover.

2004 models use common DC for controls of the AC & Gas functions...one set of t-stats....dual on/off switches inside RV

There are NO resets since 2004 versions...ECO high temp t-stat self resets when temp drops below 150*F (trips at 180*F)
The RED Fault light is triggered by Gas Flame failure or ECO opening (AC or GAS operation)

Element is still on backside for the Atwood versions

[amosnandy]

Originally Posted by DavidTL

Good day to one and all! I have a 40' 1997 CC Magna. The water heater is an Atwood unit. I am trying to run it on shore power rather than LP. The switch inside the galley is simply an ON/OFF type with no selection for LP or Elect. The unit fires up on LP just fine, but I have zero clue how to make it run on AC. I turned off the LP which obviously extinguished the flame, and now the RED indicator on the switch is illuminated. Any assistance on this would be GREATLY appreciated! --David

The red indicator light shows that the water heater is not lighting or it has over heated. Either propane or electric.

We need to know the model number of the Atwood water heater. Some are gas only, some are electric gas. I find it hard to believe that Country Coach installed a gas only unit, but in that age bracket it is possible. Country Coach was a higher end unit and I would think it would be combination.

On my Winnebago the gas water heater switch is on the display panel in the galley. The 120 electric switch is in the wall between the galley and the bathroom. It is very obvious. When off it is dark, when on it is illuminated. If turned on when not connected to shore power, it will still light up, but it is not heating water. I assume the light is 12 volts, and the switch trips a relay somewhere via 12 volts. It might go straight to the control panel and turn on 120 to the element. The element is on the back of the heater, but Winnebago hung it down under the coach, in a compartment. From the back side there is a large round cover with 4 screws that you remove if you need to get to the back of the heater.

Some with gas only have installed a "hot Rod" which is just an element that screws into the drain hole. I'm not a fan, because if not wired properly the ECO thermostat that shuts the unit down does not if not properly wired through the Temp thermostat and the eco thermostat.

If in fact, you look the model number up and it is gas/electric you need to find where the electric switch is. I doubt it is just a breaker you turn off and on. Breakers should not be used as switches. The proper way is to install the 12 volt connection connection that goes to the control board and the turns the 120 volt on. Then of course you would have to find 129 volts somewhere to power the element.

Not knowing your model, a lot of gas only units had a plug that screwed into the tank from the back and you could install the correct eating element and wire it to the control board, there for allowing the temp thermostat and the eco thermostat to work properly. I have seen improper installations where the 120 element does not shut off and the pop off pressure valves opened because the water temp was too high.

[birdhunter]

No matter what the control/switch setup may be, if you want to determine if you have an electric element in your Atwood water heater all you need to do is look at the back of the water heater and you will see back end of the element and the AC wiring to it. On mine at least there is also a separate breaker for the electric water heater element in the AC breaker panel.

[DavidTL]

I REALLY appreciate all of your input! Yes, I have a breaker labeled Water Heater. I located the back of the unit and found that the tank had been replace back in 2017. The installer never hooked up the VAC wires. I have remade the connections and am awaiting any heating results. The yellow wire that goes to the control board outside, appears to be routed correctly. I will advise later as to the results! Once again, Thank You SO much for your insights on this!

[Old-Biscuit]

Originally Posted by DavidTL

I REALLY appreciate all of your input! Yes, I have a breaker labeled Water Heater. I located the back of the unit and found that the tank had been replace back in 2017. The installer never hooked up the VAC wires. I have remade the connections and am awaiting any heating results. The yellow wire that goes to the control board outside, appears to be routed correctly. I will advise later as to the results! Once again, Thank You SO much for your insights on this!

2017 model uses 12VDC for electric and gas
Should be Dual on/off switches inside...one for GAS and one for Electric
Can not just wire the 120VAC directly to the element as that would bypass the Set of T-stats and circuit board controls
**Element would be energized continuously

Yellow wire sends 12VDC to DC Relay inside the protective cover over the element on backside
120VAD Hot goes to that DC relay...when closed it then goes to element (Black Wire)
White wire from element goes back to AC Panel Neutral Bus Bar





Here is the Wiring Diagram for that model




Here is a service manual...see pgs 23-25 for conversion from pre 2004 versions to post 2004 version
https://manuals.heartlandowners.org/...e%20Manual.pdf