I have a Atwood gas/electric water heater with DSI and it works fine on electric but does not work on gas. The gas valve does not open, the ignitor does not fire, the red light on the switch panel does not light up. I bypassed the thermostat and still doesn't work. Is there a 12 volt fuse somewhere for the gas operation?

Can you post the model number of the heater? and what year it is? The controls have changed over the years. On the "newer" Atwood's, the "same" electric controls run both gas and the electric element. On the "older" Atwood's, the electric had separate controls and the gas had it's own. Somewhere in the 2002 to late 2003, the new style came into play. And even on the older ones, there was a few generations. We need to know what model you have to help better. What it sounds like in your case, is the safety circuit is not being made. And it sounds like you have the older version where the electric element controls are on the inside of the camper side of the heater and not outside compartment with the gas valve. Make sure 12 volts is actually going to the control board as a starting place. I have not seen Atwood put a fuse on main power to the system but your camper mfg might have. Common causes have been regardless of version, corrosion on the circuit board plug so the connections do not work. Remove the plug, clean and put the wire connection back on. Sometimes just unplugging and re-plugging a few times gets it going. Corrosion on the high temp limit CO thermal disk switch terminals. This looks just like the thermostat just at a higher set point. But this only affect the gas valve, not the igniter. Corrosion on the thermal fuse wiring if your vintage has the thermal fuse. This is for a fire or excess heat in the outside compartment. This is a very small thermal fuse that has a clear plastic cover over it. The connections on the ends get cruded up and the circuit will not make. You will not get a fault light until the system actually try's to fire the igniter and the gas valve. The fault light is only for an ignition failure once the system try's to light. Since you hear no, thunk of the gas valve opening and no click, click, click of the igniter, you never made it past the safeties to allow the gas valve and igniter to start.Hope this helpsJohn

It's a 2007 and the model is GC6AA-10E. I cleaned the terminals on the circuit board and I have 13 volts coming into the circuit board via the orange wire on the top plug

13V on Orange wire from 'Gas' On/Off Switch to circuit boardSo with gas switch ONCheck for DC Voltage on Brown wire (very bottom one---BRN 1 ) to thermal fuse ...to t-stat...and back to circuit board on brown wire (top one--BRN 3 )This circuit MUST make up before DC Voltage can go to spark/gas valveThermal Fuse blows at 190*F...one time fuseT-stat has to have DC Voltage to & thru it ---- water temp has to be below 110*F for it to CLOSEConnectors need good contact on boardThen should have DC voltage on red wire (RED 4 ) to ECO then to Gas Valve solenoidCheck all groundsWorks on Electric ---same circuits(thermal fuse/t-stat/ECO etcSO could be bad 'gas circuit' on board

bjarnold wrote:It's a 2007 and the model is GC6AA-10E. I cleaned the terminals on the circuit board and I have 13 volts coming into the circuit board via the orange wire on the top plugOK this helps greatly knowing you have the newer control system. You said this"bjarnold wrote: Atwood gas/electric water heater with DSI and it works fine on electric but does not work on gas. The gas valve does not open, the ignitor does not fire, the red light on the switch panel does not light up. I bypassed the thermostat and still doesn't work.On that newer unit, the control board runs both the gas and the electric relay to the electric element. The safeties are working for both. Meaning, if it works on electric, then the T stat and the Thermal fuse are or were working. Your's does have the thermal fuse. Or at least the part number shows it does. This is a small resistor looking deceive that is normally plugged onto the terminals of the T stat with a clear tube cover and and then the brown wire on the end of it goes back to the control board. The thermal fuse is called "thermal cut off" in Old Biscuit's diagram. Have you tried this back again on electric? OR do a voltage check on the control board pin that has the brown wire from the thermal cut off fuse that goes back to the control board. Do this at the board so you know the safety circuit is in tact. Point being, need to make sure you did not make the safety circuit not work by fiddling with the wires. Easy to do. If it works on electric and it does not work on gas, and while on gas it does not start the ignition (click, click, click) and no loud clunk of the gas valve, you "might" have a PC board issue. The board sends ignition signal through the hi tension wire. And the board sends the 12 volts to the ECO switch and the gas valve.If the board has 12 volts going in the orange wire, means gas mode, and the safety circuit is working, the only thing left is the control board. It would be odd that both the gas valve and the igniter would die at the same time but not impossible. You can put a volt meter on the gas valve and ECO wiring and look for 12 volts but the gas valve makes a load clunk when they engage. You can hear it if you are outside and someone turns on the gas switch inside. Atwood service centers should have a board tester to tell you if it is bad. Hope this helpsJohn

When it happened on my older 2008 unit, the gas valve was sticking, had to tap it to free it up. When it happened again on my new 2016 TT, the board was bad.

Atwood Water heater won't work on gas | Good Sam Community

14 Replies

JBarca
Nomad II
Feb 12, 2017
bjarnold wrote:
FIXED- I checked the part number on the circuit board on my Bounder and it matched the trailer. I swapped the board on the trailer and it fired right up

Thanks for reporting back. Yup, this was pointing to the board, now you ruled it out!

Look at all your learned though. Next time you are armed to trouble shoot the whole thing!
Old-Biscuit
Explorer III
Feb 12, 2017
bjarnold wrote:
For whatever reason he said he had the inverter installed and never used the gas function. I filled the LP tanks and fridge works fine on gas so I am going to leave it that way. The only reason I question the inverter is that is the only thing I unhooked after buying the trailer and wasn't sure afterwards if that could cause the water heater issue. I measured 12 volts with a voltmeter at the orange wire going into the control board. The brown wires have no power

bjarnold wrote:
FIXED- I checked the part number on the circuit board on my Bounder and it matched the trailer. I swapped the board on the trailer and it fired right up

As I posted earlier.
Check BROWN wires....no power then bad board

Nice to have another board to swap with.
IF you plan on replacement.......Dinosaur Electronics Board----MUCH better quality/pricing
bjarnold
Explorer
Feb 12, 2017
FIXED- I checked the part number on the circuit board on my Bounder and it matched the trailer. I swapped the board on the trailer and it fired right up
bjarnold
Explorer
Feb 12, 2017
For whatever reason he said he had the inverter installed and never used the gas function. I filled the LP tanks and fridge works fine on gas so I am going to leave it that way. The only reason I question the inverter is that is the only thing I unhooked after buying the trailer and wasn't sure afterwards if that could cause the water heater issue. I measured 12 volts with a voltmeter at the orange wire going into the control board. The brown wires have no power
Old-Biscuit
Explorer III
Feb 12, 2017
bjarnold wrote:
I had a local Atwood dealer check the board. The only tester they had was an old school Dinosaur board tester. The guy said it may or may not work with my style board. They hooked it up and got the gas valve and ignitor to operate on the tester. However it is still not working on the RV. It still works great and electric mode but not gas. I am still getting 12 volts to the orange wire going into the board but no power going to the gas valve or ECO switch

Did you check........do you have DC on the BROWN wires ???

Without THAT circuit getting 12V DC then the RED wires to ECO/Gas valve and Spark Electrode will NEVER get DC Voltage-----

Gas Switch ON
DC to circuit board via ORANGE 1
DC from circuit board to thermal fuse/t-stat BROWN 1 then back to circuit board via BROWN 3
DC from circuit board to ECO/Gas Valve via RED 4 (for 6-8 seconds while DC is sent to Spark Electrode)
JBarca
Nomad II
Feb 12, 2017
bjarnold wrote:
The previous owner had an inverter installed so he could run the fridge on power instead of gas. I unplugged the inverter since I don't plan on any dry camping anytime soon. Could the 12 volts on the water heater be tied into that?

Well, not following this exactly. An "inverter" uses 12 volts DC to create 120 volts AC.

Odd your prior owner actually used an "inverter" to run the fridge on the electric element. Why did he not just run the fridge on gas and be done with it? That is why they are made that way. Even the fridge has to have 12 volts DC to run the control system regardless if it running on gas or electric if he had an RV fridge. Like a Dometic or Norcold.

Your hot water heater has 12 DC volts going to it. You said the electric side of the HW heater worked. Even when using the electric element, the control board has to have 12 DC volts to turn on the 120 VAC electric element. The 12 volts DC turns on a relay in the back of the heater to then turn on the 120 VAC element. And you said the orange wire when on gas had 12 volts to it. Did you physically measure that 12 volts at the heater control board or somewhere else?

How are you thinking the "inverter" is affecting the HW heater?

There may be more to the inverter thing, but need more info.
bjarnold
Explorer
Feb 12, 2017
The previous owner had an inverter installed so he could run the fridge on power instead of gas. I unplugged the inverter since I don't plan on any dry camping anytime soon. Could the 12 volts on the water heater be tied into that?
JBarca
Nomad II
Feb 11, 2017
That is odd, he got the igniter and the gas valve on a bench test to work but it does not work in the camper?

This might be a long shot, but check the case ground (DC neg) going to the heater case. An ohms check to a good ground will do, or bring a temporary new ground and make sure the metal that the gas valve is on gets it OR put your volt meter between the orange hot wire and the actual body of the gas valve. If the gas valve has a ground, the meter should work.

While the electric works, in this case the board provides the 12 volt DC to a relay on the back side of the heater. Looks like this.

The relay gets it ground from a DC common wire and is a different location then the igniter and the gas valve.

And the pc board, gets it's ground through the incoming wire harness.

If for some odd reason, the case ground is bad on the outside heater area, then the board is sending 12 volts positive, but if there is no ground on the case, the valve will not work or the ignition as they are both almost connected together and they are only fed with a positive wire from the board, case ground creates the other wire.

If the board bench tested, it should work in the camper, unless the ground is bad for the gas valve and the igniter or the board has intermittent issues.

Hope this helps

John
bjarnold
Explorer
Feb 11, 2017
I had a local Atwood dealer check the board. The only tester they had was an old school Dinosaur board tester. The guy said it may or may not work with my style board. They hooked it up and got the gas valve and ignitor to operate on the tester. However it is still not working on the RV. It still works great and electric mode but not gas. I am still getting 12 volts to the orange wire going into the board but no power going to the gas valve or ECO switch
bobndot
Explorer III
Feb 11, 2017
When it happened on my older 2008 unit, the gas valve was sticking, had to tap it to free it up.
When it happened again on my new 2016 TT, the board was bad.