Dometic Atwood water heater not working on gas

[John Matt]

Good morning to everyone. I’m having problems with my hot water heater model # GC6AA-10E it works on electric, but not gas. These are the things I’ve tried: propane bottles full and on, checked all fuses in and out, checked connections on board all are clean, checked thermal fuse good, checked panel switch inside and everything lights, changed fuse on board outside good, pulled out the igniter out to make sure nothing blocking path, pulled out the little screw hole it’s clear, I’m getting a spark for ignition. I was thinking it maybe the board, but now I’m thinking it may not be getting gas. So could it be the regulator on the hot water heater. I did notice when I put the switch on for the gas the fault light comes on after the ignition try’s to light after 3 attempts. I appreciate any information you can give.

[MSHappyCampers]

Hi ! Welcome to IRV2! We're sure glad you joined us!

One of our experts will be along to offer advice! On my WH the red light on the inside switch comes on and then goes off after the heater ignites.

Good luck, happy trails, and God bless!

[Ljwt330]

Originally Posted by John Matt

Good morning to everyone. I’m having problems with my hot water heater model # GC6AA-10E it works on electric, but not gas. These are the things I’ve tried: propane bottles full and on, checked all fuses in and out, checked connections on board all are clean, checked thermal fuse good, checked panel switch inside and everything lights, changed fuse on board outside good, pulled out the igniter out to make sure nothing blocking path, pulled out the little screw hole it’s clear, I’m getting a spark for ignition. I was thinking it maybe the board, but now I’m thinking it may not be getting gas. So could it be the regulator on the hot water heater. I did notice when I put the switch on for the gas the fault light comes on after the ignition try’s to light after 3 attempts. I appreciate any information you can give.

I agree, from what you've posted, that it appears to be a gas delivery issue.

First question, is this a new issue?

Second question, have you used your other gas devices, like the stove top, since this issue arose?

You need to be certain you have gas flowing through the system so if you can use your stove top, gas should be reaching the water heater as well.

Since you have spark, 12v is being supplied as necessary. That same voltage that is causing the sparking should also be opening the gas valve at the same time. When the switch to use gas is turned ON, you should hear a distinct "click" from the gas valve and a "tick, tick, tick" from the igniter simultaneously. You can check this by standing by the open heater access panel while someone turns on the switch for gas.

If you hear the valve open, check the burner orifice and the end of the tube. Carefully remove the orifice and see if you can blow through it. If not, soak it in alcohol and repeat trying to blow through it. Do not push anything into the hole.

If the orifice is clear, you need to confirm that gas is coming from the open valve. You should be able to smell it during the time the igniter is sparking.

[Old-Biscuit]

Sounds like gas valve solenoid issue

Couple things:
Check that DC is going to/thru ECO and to gas valve solenoids (RED wire)
Check Solenoid resistance thru them (unplug red/black wires (1 solenoid at a time noting which is red or black terminals)
Resistance S/B ~48ohms Each....both solenoids have to work to open gas valve

You can check the 'Valve Track' using a voltmeter and checking continuity
TO TEST VALVE TRACK: (unplug 4 pin & 6 pin connector from circuit board to prevent any shorting out)
Then on 6 pin edge contacts----
Place negative lead of the multi-meter to ground (green wire) track of edge connection and positive lead of the multi-meter to valve (red wire) track of edge connection.
If no continuity, this indicates a blown valve track.

Pin Numbering
4 pin top to bottom
4---Empty
3---Brown/T-stat
2---White/Electric
1---Orange/Gas

6 pin top to bottom
6---Ground/Chassis
5---Ground/12VDC NEG
4---Red/ECO-Gas Valve
3---Blue/Fault Light
2---Yellow/DC Relay
1---Brown/Thermal Fuse



Fault Light/3X attempts to Light gas
Safety feature. Circuit board will make 3 attempts to ignite the gas AND PROVE it lit (via flame rectification-----milliamp current circuit board must sense)
No ignition/flame proof then circuit board shuts down, triggers fault light/'locks out' functions until reset
This prevents accumulation of raw fuel ===gas build up BOOM

Can happen if propane has not be used in a while.....flow as to be established at each propane appliance (fridge/water heater/furnace have this safety feature)

Reset...turn switch OFF wait 5 econds turn switch back ON

[John Matt]

Originally Posted by John Matt

Good morning to everyone. I’m having problems with my hot water heater model # GC6AA-10E it works on electric, but not gas. These are the things I’ve tried: propane bottles full and on, checked all fuses in and out, checked connections on board all are clean, checked thermal fuse good, checked panel switch inside and everything lights, changed fuse on board outside good, pulled out the igniter out to make sure nothing blocking path, pulled out the little screw hole it’s clear, I’m getting a spark for ignition. I was thinking it maybe the board, but now I’m thinking it may not be getting gas. So could it be the regulator on the hot water heater. I did notice when I put the switch on for the gas the fault light comes on after the ignition try’s to light after 3 attempts. I appreciate any information you can give.

I now don’t think I’m getting a spark on the gas side. I heard the gas trying to kick on 3 times. So do you think it’s the black box? I put a match in air vent control and it fired up but went out shortly afterwards.

[Old-Biscuit]

Check the gas valve as noted in my 1st post

Check continuity of spark electrode
Disconnect wire from transformer on circuit board and check continuity ---wire connector to end of electrode
Clean electrode using emery cloth to remove soot/carbon
Set spark gap 1/8" - 3/16"


CAUTION....this next test could get you zapped
**Disconnect Spark Electrode wire from transformer
Strip both ends of a piece of wire
Connect one end to transformer terminal
Hold wire with insulated pliers and hold other end close to spark electrode mount screw / Ground
THEN have someone turn GAS switch ON (cool water temp so t-stat closes)

If circuit board is good....big spark (~2000VDC)...bad spark electrode
If circuit board bad....no spark

[Ljwt330]

Originally Posted by John Matt

I now don’t think I’m getting a spark on the gas side. I heard the gas trying to kick on 3 times. So do you think it’s the black box? I put a match in air vent control and it fired up but went out shortly afterwards.

The igniter serves both as the sparker and to prove the flame is burning. Your symptoms are consistent with a failed igniter probe since it neither sparks nor maintains the manually lit flame.

[Teamfoxy]

The igniter is only about $7 on Amazon so I always keep spare. I've had the oriface clog a few times and its not hard to remove it and clean it with alcohol and compressed air. Usually you can hear an erratic flame before it stops working, but we have a propane only waterheater so are used to the sound of it working correctly.

[Old-Biscuit]

Originally Posted by Teamfoxy

The igniter is only about $7 on Amazon so I always keep spare. I've had the oriface clog a few times and its not hard to remove it and clean it with alcohol and compressed air. Usually you can hear an erratic flame before it stops working, but we have a propane only waterheater so are used to the sound of it working correctly.

Careful using compressed air to blow thru orifices
They are designed for less then 0.5 psi (1/2#)
Higher pressure then that can damage them......
*some are laser drilled, have ruby inserts, microfilm inserts etc