Issues with Atwood Water Heater

Steve Collins · 10-06-2010, 08:08 AM

I encountered some difficulties with the water heater over the past weekend. It's an Atwood GC6AA-9E LP Gas/110vac model.

It rained heavily off and on for the two days before we left for the weekend, and it rained intermittently while on the road to the campground. We arrived about 1 PM and although the rain had stopped, the rest of the day was damp and chilly.

When we arrived, I turned on the water heater for gas operation (no hookups in this campground.) It fired right up, but shut off after just a few seconds of flame. No matter how many times I shut it off, let it reset, and then on again, it did exactly the same thing.

Generator hours arrived at 4 PM so I dug out the wife's hair dryer and went after the control board and wiring. After 20 minutes of that, it still did the same thing. I also switched it over to 110vac operation for a while just to warm up everything and to have some hot water now.

Then I checked the thermostat and ECO switch. The thermostat looked like it was not fully seated so I removed it and reinstalled it. Same for the ECO. Still the same results.

Next, I bypassed the thermostat with no change.

Then I bypassed the ECO, it fired up and it stayed running. Partial success! (I shut down the 110vac operation at this point.) At first on gas, it would not shut off on its own so I let it run until the water was hot enough and turned it off at the switch.

(The manual names the ECO switch several times, but doesn't mention what its function is. mbart5fan has a detailed service manual so between that and a quick Google via the BlackBerry, I learned that the ECO is basically a high temp thermal cutoff switch. It looks just like the thermostat and is positioned right along side it. BTW, you can buy an assembly that has both on it for between $11 and $15 plus shipping on the internet.)

I then reconnected the ECO switch and tried it again. Voila, it stayed running! At this point, I got diverted by other things, and forgot to manually shut it off. When I came a half hour later, it had shut off on its own and appeared to be functioning normally all around. For the rest of the weekend which was dry and sunny, but cool, it worked just fine.

In summary, it appears to be a moisture issue, but not one that simply drying out the control board seems to solve. The control board is encased in epoxy or some similar goop so it may take more time to dry out than I think it should.

When I first opened up the heater from the outside, there was no sign of water spray or drip on anything but it was all cold and maybe a touch damp from condensation, but not actually wet. My initial thought is to fabricate up a shield to keep moisture from getting at the control board, but given that drying it out didn't seem to help, that may not be of much use.

Bypassing the ECO obviously got it going properly, but it then reverted to normal function both with and without the ECO connected so that is a bit of a puzzle to me.

Anyone have thoughts or ideas? I am stumped at this point.

GoodoleBob · 10-06-2010, 10:18 AM

Steve...I had pretty much the same issue with my Atwood this past weekend. I presumed the wind driven rain didn't help the situation at all and I reverted to using it on electric the rest of the weekend. Now I will be watching this thread to see if there is a bigger picture I should be aware of. I personally prefer my Atwood on electric over propane, but I do want the unit to be functional on both regardless.

Bob

Gene · 10-06-2010, 05:47 PM

All that continued moisture (and we DID have a lot!) just sort of works its' way into all the connections even if they don't look wet. Even a hair dryer doesn't help if there is a little corrosion started, sometimes so little you don't see it.

That said, let me digress a moment. ... Years ago I used to do mobile outdoor sound systems for dog shows. I had constant problems with intermittent speaker connectors and plugs. I tried all the cleaners and greases but none worked more than one day. I tried WD40 and that worked. I sometimes had to spray connectors a year later. I have also used WD40 on the edge connectors of computer printed circuit boards.

So ... I would recommend removing each connector, one at a time, spray with WD40, shake off the excess and reconnect. You can also do it to the module connector. Don't spray the insulator for the igniter wire.

I also recommended it to someone on RV.net that had tail light problems. After all the cleaner and grease stuff didn't work he had success with WD40

**JohnB** · 10-06-2010, 07:22 PM

Steve I'm digging for info now to confirm my thoughts but need this info.

When the gas blew out, did you get a DSI fault light inside?

Does your vintage even have a DSI fault light? It may only be a little red LED on the tank panel. May not even have a label

When the gas blew out, did the igniter try to refire but itself? Or only when you reset the power and started over?

Thanks

John

Steve Collins · 10-06-2010, 08:00 PM

John,

The DSI fault light is part of the heater switch. If the heater fails to start, the light comes on, and it did, repeatedly...

When the flame went out, it did not try to re-fire by itself. Only when we did the reset at the switch did it try to fire again.

**JohnB** · 10-06-2010, 09:25 PM

Steve here are some thoughts.

You have given good info so here goes based on what you have said so far.

1st as you stated the ECO switch stands for emergency cut off. It is a normally closed thermal disc switch that opens when the temp reaches 180F.

The T-Stat switch is the thermostat. It is another thermal disc switch and is normally closed and opens when temp reaches 140F.

Here is a limited service manual on your HW heater generation. http://www.nwrvsupply.com/manuals/at..._operation.pdf

I have the master service manual however it is 27 meg and I can’t even email the thing. It is 186 pages and covers Atwood HE heaters, stove and the furnace. If I can figure out how to chop it up I’ll send it to you.

Here are my thoughts. The ECO switch is a normally closed switch. Jumping it should not have an effect and it should not of made any difference to not letting the system not shut off. It is only ever intended to be used as an emergency as it opens up at 180F. The T stat is what is suppose to shut the heat down at 140F so the ECO should never come into the equation unless the T stat never works or the PC board never shuts down the call for heat. The ECO is hard wired in series with the gas valve.

OK with that said how did it seem to help you when fiddled with it and when you jumped it seemed to do something.

Try this on for size and see if it fits as it at least adds up electrically to what you stated happened. Since the heater fired off the 1st time, that means the T stat, the thermal cut off and the ECO was working. The DSI (direct spark ignition) system was at that point working too. The call for heat from the PC board 1st sends power to the gas valve at the same time it fires off the ignition. Once the gas lights, the flame heats the spark electrode, creates a very small millivolt signal and then sends it back to the PC board that flame is present and shut down the igniter. The Flame then continues to burn and all is happy.

But then poof the flame goes out. Nothing. I am making an assumption when the poof and roar of the flame when out, did you get a DSI fault light inside? Yes or no?

OK so you turned off the power to the heater and turned it on again. It fired up and then poof went out. So not you start testing, fiddling with wires and put the jumper on the ECO valve and it starts working. GREAT. But then it appears to not want to shut off. Then later the things starts working OK eventually

Well OK here is what I can add up to what “might” have happened. I have 2 possibilities and or both at the same time.

No 1. The thing is damp from the rain. Even the hair dryer trick did not work. But what did get it to work was, fiddling with the ECO wires and jumping the ECO. Well what you could have done is actually make the connection in and or out of the ECO work. Slight corrosion from the wet on the terminals got scraped off or even more so, you jumped over the already normally closed ECO switch allowing better contact then thru the ECO. Since the unit fired up, the connection was intermittent. The Heat may have affected the connection and dropped out the gas valve yet again. When the gas valve drops out for any reason that the PC board does not tell it too,. the flame sense take over, sees no flame and then shuts the unit down on safety. Basically the wiring connections on the ECO, the gas valve or the wiring from the ECO back to the board had connection issues. Gene talked about the WD40 trick. I never knew that one but the dielectric grease yes. I would say do each connection with steel wool or some cleaner then treat WD 40 or dielectric grease. All of them. Even the T stat area.

No 2. In my master service manual it talks about the burner tube. See no 4 here.

Bascially if the burner tube deflector disc is not parallel to the end of the gas tube it will not spread the flame out properly and that can have an effect getting heat to the flame sense electrode. If this is occurring, then the flame sense is not satisfied and will shut the unit back down in seconds as the flame is not heating it enough. This one is a long shot unless you had the burner tube out and some how it got dinged and due to the damp the flame did not spread out as good as it usually did to over compensate for the deflector disk. It is something to check and at least would create the problem you noted.

I think no 1 is the issue with the higher chance of being the problem.

OK now in light of all that….. does that add up to explaining what happened? I’m not there to poke and look, just listening to your good memory write up and in what order you did it in. If it does not add up, then fill in some more info on why and what else may have occurred. After seeing you 2nd note on the DSI faults it added more to, something killed the flame, so what was it? The DSI fault can occur any time the unit calls for flame. And I think the ignition will only fire when the system 1st shut down the heat then fires it back up. So you will only get one set of ignition trials. This Atwood is not wired like the LP heat on the Dometic fridge which will try and fire off if the flame blows out and it does not yet shut down on safety.

Hope this helps

John

**JohnB** · 10-06-2010, 09:31 PM

Steve, check you email. I found a smaller Atwood HW heater service manual. Only 40 pages in place of 186. This is the one I gave Mike last year when he has issue that he came over with for you. The power of Sunline Club. One member helps the other, then the other helps someone else. What a bunch of helpful happy campers we are.... Spread the word!

Gene · 10-07-2010, 09:57 AM

Quote:

Originally Posted by Steve Collins

...
Then I bypassed the ECO, it fired up and it stayed running.
...
I then reconnected the ECO switch and tried it again. Voila, it stayed running!
...
Bypassing the ECO obviously got it going properly, but it then reverted to normal function both with and without the ECO connected so that is a bit of a puzzle to me.
.....

Steve I think you found your answer but it was not the ECO itself, it was the connection to the ECO. Sliding the connection off and putting it back on was what cured it. I do think the WD40 thing above will take care of it.

Gene

Poppy & Nana · 10-07-2010, 01:27 PM

Hey guys remember John & Kim could not get their fridge to fire up on propane either - after driving the the rain for hours......they ate dinner with us and then POOF it worked!!!!

Steve Collins · 10-07-2010, 03:17 PM

John sent me the maintenance and troubleshooting manual by direct email, and thank you sir!

I am now fairly certain that moisture and oxidation on the various terminals is the combination that caused the problem.

We've had heavy rains while camping in the summer and this doesn't happen. I think the cooler fall weather plays a part as there is likely to be more condensation on the connections.

So I will be cleaning all the connections before I put the trailer away for the winter.