Atwood Water Heater Won't Operate on Gas

[purple222]

My LP/110V Atwood works great when I'm hooked up, but doesn't work at all on gas. Is the 110V system separate from the LP side because the 12v side doesn't seem to be getting power (when I remove the 12v thermostat and put the wires together there's no spark)?

I have been told there should be a manual ignitor inside for the gas, but all I see is the one on/off switch inside. Gas works fine for the fridge and stove too.

I feel like I'm missing something really obvious here.

Thank you.

[DFord]

Go to Dinosaur Electronics http://www.dinosaurelectronics.com/Tips_Tricks_Page.htm or call and ask for help from Joe Haggerty. He may be able to help you troubleshoot the problem and recommend a solution. I got two day service across the country from http://www.americanrvcompany.com/

[purple222]

So the fuse blew, replaced the fuse, now it tries to light but cannot.

I think I need professional help.

[enblethen]

Check for power at the circuit board connector on wire coming from the switch. No power could be switch or fuse.

[purple222]

Alright, at the risk of being lazy, I'll say that I got a new thermostat, ECO, and thermal fuse. It all worked brilliantly, but soon it would shut off after just a few moments of fire. Now, I can't make it work by connecting the wires together, bypassing the thermostat. There's no current. Am I doomed to buy a new circuit board?

[DFord]

purple222 wrote:
The board still has no light, but when I remove the fuse AND the thermostat I get ignition. I think someone miswired the switch inside so that the unit is either on 110v or gas, so ON for one is OFF for the other.

Anyway, looks like a bad thermostat. Still no light on the board but we have spark and gas! 🙂

Did you test the thermostat with an ohmmeter? I would expect it to be closed until it reaches its set point around 140F degrees where it should open. If it's open at room temp, by all means replace it. Test the new thermostat with the ohmmeter before you install it to double check.

[wa8yxm]

On SOME Atwood and Suburan water heaters both there are parts in common
On others, not so.

On most modern Atwood the thermostats and control board are common.. But again, not all.

If yours is like mine (Control and T-Stats are common) then the following furnace tribble shooting guide may help.. I'm told I did not miss much when I created it,, Ignore all references to time delays save for the 3 second one, Blower and sail switch, and cool down periods.

When the T-Stat calls for heat the control board starts the blower (1)
The blower blows closing the sail switch (2)
The control board then opens the gas valve (3) and begins sparking (4.1)
Gas Flows (5) And ignitets (4.2)
The flame heats the flame sensor (5)
The flame sensor sends .480 volts to the control board (6)
which then detects the .480 and continues operation (*)
When the T-stat says "Enough already" (RV is now warm)
The control board shuts off the gas flow (*)
and then turns off the blower after a cool down (*)

*: At nearly every step the control board is involved. IF IT IS BAD, things will not work.. I recommend replacement boards from Dinosaur boards.. When Mine went out the Dino board was less than half the price and when opened the box the quality of construction and workmanship, and then design was very clear to my trained eyes.

1: No 12 volt to furnace, blower motor shot
2: Low 12 volt, air ducts clogged, blower "obstructed" bad sail switch
3: Bad solenoid, Clogged Gas Jet
4: .1: Bad ignition circuit (high voltage) on control board. .2: Points too wide (Very common it seems)
5: These do not often fail but they can
5: Bad connection, NOTE:
5 and * Bad wire.

* applies to all steps by the way So does bad wire/connection.

On mine, it was the control board (both furnace and water heater) Easily replaced. One screw, and some you can not go wrong electrical connections.

[Old-Biscuit]

purple222 wrote:
It looks intact but doesn't seem to be moving current along, I figured best thing would be to just order a new one. That and the thermostat are the only two things holding up the works (no light on the board seems not to be an issue) so I ordered both.

So my only remaining problem will be no heat, but at least I live in Florida.

Light should be a Fault Light------comes on when spark occurs but no main flame lights off.
With main flame lit.....pull one of the RED wires off ECO and see f light comes on?



How did you 'test' the thermal fuse and/or t-stat?

Unplug thermal fuse and plug brown wire directly onto t-stat.
If t-stat is good propane will work
Or you can plug thermal fuse into brown wire from t-stat going back to circuit board (bypassing t-stat). If thermal fuse is good propane will work

Thermal fuse is one time deal....blows at 190*F
Must replace when it blows
T-stat Opens at 140*F and Closes at 110*F
ECO Open/180*F--Close/150*F


ON/OFF Switch..that switch should just be for propane operation.

Electric operation should be via a local switch on cover over electric element (backside bottom of WH Tank)

If someone rewired the 12V DC Propane switch to operate the electric element it has 120V AC and 12V DC to/thru it



So what's up with furnace?
Which model Atwood and what is it doing/not doing??

[purple222]

It looks intact but doesn't seem to be moving current along, I figured best thing would be to just order a new one. That and the thermostat are the only two things holding up the works (no light on the board seems not to be an issue) so I ordered both.

So my only remaining problem will be no heat, but at least I live in Florida.

[enblethen]

The two red wires should be going to the ECO.
The two brown wires go to the thermostat.
Adjacent to the eco and thermostat under some tubing is a thermal fuse. Did you check it for continuity?

[purple222]

The board still has no light, but when I remove the fuse AND the thermostat I get ignition. I think someone miswired the switch inside so that the unit is either on 110v or gas, so ON for one is OFF for the other.

Anyway, looks like a bad thermostat. Still no light on the board but we have spark and gas! 🙂

[purple222]

Thank you, will update.

[Gjac]

The manual that phays posted tells you how to trouble shoot the board and the other components of the systems. If the board is green you can see all the components and look at the backside for any burned tracks on the board and the front to see any components that look burned or melted. The potted board you will have to check with your ohm meter. I would check and clean all the connects first especially the grounds and igniter to see if that helps.

[phays]

Download this manual

Atwood service manual

[Kayteg1]

I just had to replace electronic board on Atwood furnace.
About $90 for Dinosour on Amazon.
New board are convertible, so you can use it on WH. refrigerator or furnace with fan delay.