Water Heater Ignition Problem

[HawkeyeJones]

This is regarding an Atwood GH68E water heater installed in our 1998 Winnebago Minnie Winnie Class C. It's on a simple switch activation system.

The presenting problem is simple enough: I flip the switch, the Pilot Out light comes on for a few seconds, then turns off as it should. However, the light then turns on again, indicating a system lockout. I can hear a small ignition 'click' in the water heater compartment, but the propane does not audibly flame on as I'm used to hearing.

I've gone over the troubleshooting section of the water heater's manual, but I can't tell what the deeper problem is or even where to begin. This is my first time tinkering with a water heater. Any advice on where to start?

 

[Mark_K5LXP]

Since the pilot out light is working it can be assumed the control board has power. When you activate it with the switch from a cold start, you should hear (and if standing watching it, see) the tick-tick-tick of the ignitor sparking in the burner tube. If you see the spark but no whoosh, you have a fuel problem. If it's not sparking, it's electrical. Could be as simple as the ignitor is misaligned or there's impeding crud, so first determine if it's fuel or fire and keep peeling back the possible causes.

Mark B.
Albuquerque, NM

 

[John From Detroit]

This is a common failure of Atwood water heaters (And Surburan) Due I Think to the single wire ignition system. I just typed this in another thread so. This is what I THINK is happening to the boards.. NOTE the Dino board I used was for my Furnace. I could not get the proper board in time when my water heater board failed and had to use an OEM replacement. Was not happy about that (They had the Dino board but not the needed adapter for my heater).

A friend in another area (I pointed him here) had Water heater issues (new board fixed)
Atwood and I suspect the other major suspect use a single wire ignition system .In this system the single wire carries about 1000 VAC (Based on the spark gap) to light your fire and about 1/2 volt (0.4 Back Some folks claim it's current. but truthfully it matters not if it's 0.48 volts or the current that 0.48 volts causes to flow in the wire) A solid state device switches the wire from one function to the other. What happens if it ... flubs the switch over? POP GOES THE SENSOR chip)

Dinosaur electronics on my Furnace (Same type of system) Board put in a handy dandy Gas Discharge tube right about where I think it was to protect the sensor chip.

 

[Kirk]

I flip the switch, the Pilot Out light comes on for a few seconds, then turns off as it should. However, the light then turns on again, indicating a system lockout.

The symptom could be the circuit board but far more likely is the ignitor probe, which can be purchased for around $10 and they are available from Amazon or from any RV parts store. The circuit board cold cause that problem but that would be unusual as in my experience, if the circuit board fails it doesn't even try to light as yours is.

A very easy way to see if the probe has failed would be to go outside and hold one of the butane barbeque lighters burning in the area next to the probe and see if the propane lights. If it does, replace that probe.

Since the pilot out light is working

The water heater that he has doesn't have any pilot. For furnther troubleshooting downoad this copy of the Atwood Service Manual to aid you.

 

[NY_Dutch]

I took it that he was referring to the ignition sparks as the "pilot". The GH6-8E doesn't have a pilot as you said.

 

[Tulecreeper]

The symptom could be the circuit board but far more likely is the ignitor probe, which can be purchased for around $10 and they are available from Amazon or from any RV parts store. The circuit board cold cause that problem but that would be unusual as in my experience, if the circuit board fails it doesn't even try to light as yours is.
View attachment 173879
A very easy way to see if the probe has failed would be to go outside and hold one of the butane barbeque lighters burning in the area next to the probe and see if the propane lights. If it does, replace that probe.
View attachment 173880

The water heater that he has doesn't have any pilot. For furnther troubleshooting downoad this copy of the Atwood Service Manual to aid you.

I took it that he was referring to the ignition sparks as the "pilot". The GH6-8E doesn't have a pilot as you said.

He said the "Pilot Out" light comes on, so I would think there is a pilot light.

 

[NY_Dutch]

He said the "Pilot Put" light comes on, so I would think there is a pilot light.

On re-reading, yes, he's calling the ignition failure light at the switch the "Pilot Out" light. And maybe that's how Atwood/Dometic refers to it. I haven't checked the manual for that model.

 

[Gary RV_Wizard]

Atwood heaters are available as Pilot or Electronic, but the "8E" in the model number clearly says this one is the electronic ignition type. It would be an "8P" if it had a pilot light. The wall switch/light may be labeled "Pilot Out" or anything at all, but that's irrelevant. The switch doesn't come with the heater and may not even be an Atwood component. For an Atwood electronic ignition heater, whatever light is connected to the wiring is going to signal the ignition status.

 

[Kirk]

The wall switch/light may be labeled "Pilot Out" or anything at all, but that's irrelevant.

Most Atwood brand water heater switches that I have seen have nothing on them at all if the single switch and some do say Atwood but the light is not labeled. This is what mine looks like.

 

[Gary RV_Wizard]

Most Atwood brand water heater switches that I have seen have nothing on them at all if the single switch and some do say Atwood but the light is not labeled. This is what mine looks like.
View attachment 173902

Yeap. And many RVs don't even use Atwood brand switches or indicator lights. All I'm saying is that the fact that a light may be labeled "pilot out" is not reliable to determine the kind of ignition.

 

[John From Detroit]

On my RV the water heater switches were "3rd party" part of a much larger control panel two switches with an indicator light between them One labeled GAS one Electric. I do not recall if the light was labeled "Fault" or just .. there.

 

[RVfixer1]

I have cured a lot of water heater problems for others by just do the general maintenance that should be done at least annually. I first do as posted above and watch for spark at start up. Then I clean the fuel/air tube, clean the carbon off the igniter and sensor, often being just one probe, and clean the burner. While the fuel/air tube is off remove the gas orifice from the gas valve and carefully clean it. For your problem I often find that orifice plugged. That orifice usually has a plastic insert inside. Don't use anything stronger than alcohol and low pressure air on that orifice. If you must push something through that orifice use a paint brush bristle, nothing harder/stiffer. Clean the grounds and put it all back together setting the gap between the igniter and burner per the manual...if no manual go with 1/8th inch (3/16 max) and make sure that the igniter will be in the flame.

If the above doesn't fix it...you got your maintenance done anyway and eliminated some common problem areas. If you can't smell gas, and your gas appliances are working, I'd suspect the gas valve. Before I would buy a circuit board I'd call around the local RV shops and see if one has a tester.

There are my ramblings.....again I have fixed a lot of RV gas water heaters and fridges by just doing the general maintenance. Even if you think you are current with your maintenance bugs can bugger things up in gas appliances.

 

[Kirk]

There are my ramblings.....again I have fixed a lot of RV gas water heaters and fridges by just doing the general maintenance.

I think that most of us tend to put recommended maintenance on RV appliances off until we have a problem. I used to do some of the easier parts most years.

 

[RVfixer1]

I have put off my maintenance at times. That is OK if you know how to do it and have the proper tools while on the road. I find many folks camping that have a problem, no clue what to do, no manual and few tools. I enjoy trying help them out and maybe save a trip and teach them something. Like I said very often I fix problems by just doing the maintenance. If parts are needed that is another thing.

 

[Kirk]

That is OK if you know how to do it and have the proper tools while on the road.

I was a career electromechanical technician. I guess it is like the old saying: "The cobbler's children have no shoes!"

 

[HawkeyeJones]

To settle the discussion of the Pilot Out situation: Pictured is the light on my galley control panel labeled Pilot Out, which comes on when the water heater switch is toggled, then goes out when it sparks (if it comes on again after that, it's a lockout situation). This is an electrical ignition system, not a pilot system, despite the light's label.

Substantively to the problem: I opened up the water heater and confirmed that the nodes are sparking properly. 1/8" gap between the nodes, everything clean. However, it appears no gas is flowing. I cleaned the flue and the heating tube. I've used isopropyl alcohol on the exterior of the orifice. However, the components of the valve are fused too tightly for me to remove either the orifice from the valve or the valve from the gas line. I've used liquid wrench penetrating oil to try and loosen the threads; it still won't budge. I can't put too much torque on the wrench because if I do I could rip the whole valve out of its housing. So now I'm not sure what to do.

 

[John From Detroit]

If the components of the valve are fused that tight. REPLACE IT.
But first. if you are talking a solenoid valve get either a test light and hook across it wile your parnter turns on the gas switch.. Watch for the light while the sparker starts sparking (Should be on) if it's not on (make sure light works first by the way) then the valve might not be the problem.

OR a Common license plate light socket (Two leads) and a dash indicator lamp (Blace type to fit socket) and wire it across the solenoid. LIGHT ON = Good control board bad valve. Light off = Bad board.

 

[Gary RV_Wizard]

I opened up the water heater and confirmed that the nodes are sparking properly. 1/8" gap between the nodes, everything clean. However, it appears no gas is flowing.

The heater control board only opens the gas valve during ignition and as long as the flame is burning. Lockout occurs if no flame is detected for longer than around 15 seconds. You can only detect gas flow while the igniter is sparking, or (of course) while the flame is actually burning. The igniter tip is also the flame sensor.

One common reason for failure to detect the flame is corrosion on the igniter/sensor wire where it connects to the circuit board. The ignition pulse is powerful and gets past corrosion, but the sense signal is weak and gets stopped if there is corrosion there.Clean the connection with a pencil eraser.

 

[gwinger]

Clean the gas tube to the burner. Blow some low pressure compressed air into the tube. Spider and other insects love to nest in that tube and it disrupts the gas flow.

 

[Kirk]

Let me add just a little to Gary's advice. There is an easy way to check for propane while the ignitor is sparking. Just get one of the butane lighters for a barbeque and get it burning, hold it just below area of the spark and have someone turn on the water heater for you. If there is propane you will see it light, even if it turns off again when sparking stops. I have used that method of testing many times.

However, the components of the valve are fused too tightly for me to remove either the orifice from the valve or the valve from the gas line. I've used liquid wrench penetrating oil to try and loosen the threads; it still won't budge.

At this point, do not replace anything there. In many years of maintaining my own RV water heaters and also helping other RV folks with them I have only one time had a need to remove the propane orifice. That one time was due to the fact that the RV owner had also tried to remove it and when he had difficulty, he then used something metal to run through the opening and doing so damaged the orifice. Never use anything metal when cleaning one.

And just so that you know, no matter what that red light is labeled, it working exactly as it should. Both of the two most common brands of water heaters use the same method, and both have switches available that include the light. Yours is on a control panel from the RV manufacturer which works fine, but as this picture shows, the manufacturers now label the light "reset."