water heater woes

[Martin230]

Hi everyone,  we have a heartland wilderness 25ft travel trailer, almost a year old, has been wonderful. Until now we have used the electric part of the Atwood GC6AA-10E water heater and it has worked perfectly. However now we need to use the propane part and have hit trouble......it fires up first time and burns beautifully for two or three minutes then shuts down, the DSI fault light in the cabin comes on at this point, i can hear it trying to ignite but no go. After a while the whole thing resets and will repeat the same thing.

Everything looks clean and new under the cover but I have cleaned all connections and bypassed each of the thermal sensors....still does the same thing, ignites, burns for a couple minutes then shuts down.

I can't think of anything else obvious to try and we can't get the trailer out to a sevice center, any suggestions?  Many thanks, Martin

 

[Gary RV_Wizard]

I would try vacuuming out the burner tube to make sure there are no rust flakes, spider webs, etc. That doesn't seem likely since it lights the first time OK, but it's the first step in burner maintenance.

The fact that it tried to re-light but cannot suggests a gas flow problem, but one that doesn't appear until the water heater heats up. Could be a faulty gas valve or even a faulty circuit board that quits working only after it heats up.  I'm guessing that the heater ignites OK once it has cooled down for a few hours? Is that right?

 

[Martin230]

Thanks for the suggestion, I'll try cleaning out the tube and yes it does seem to reset after an hour or so when it's cooled down. Do you know if the DSI fault light coming on indicateS that the igniter itself isn't sensing properly or could it be a number of things, including a problem with the circuit board? Thanks again, much appreciated. Martin

 

[RedandSilver]

Hi everyone,  we have a heartland wilderness 25ft travel trailer, almost a year old, has been wonderful. Until now we have used the electric part of the Atwood GC6AA-10E water heater and it has worked perfectly. However now we need to use the propane part and have hit trouble......it fires up first time and burns beautifully for two or three minutes then shuts down, the DSI fault light in the cabin comes on at this point, i can hear it trying to ignite but no go. After a while the whole thing resets and will repeat the same thing.

Everything looks clean and new under the cover but I have cleaned all connections and bypassed each of the thermal sensors....still does the same thing, ignites, burns for a couple minutes then shuts down.

I can't think of anything else obvious to try and we can't get the trailer out to a sevice center, any suggestions?  Many thanks, Martin

Did the electric part stop working?
And that's why you NEED to us the propane part of it?

IF so, I would think the electrical heating element is bad and needed replacement.

 

[Rene T]

Did the electric part stop working?

The way I read it is that the electrical side still works fine but now they need to have the propane side work. They may be going boondocking or traveling.

 

[John From Detroit]

2 or 3 minutes is about the time it takes to try try try to light (3 tries)

Then if it does not sense the flame (Even if you see it) it goes into fault mode

What can stop it from sensing flame?
Well if spiders have nested in the orifice and not enough gas is flowing (It should not look like it "lit nicely" if that is the case)
If the Thermocouple flame sensor is bad (This device generates about 0.480 volts when hot) and is not making the needed 0.480 volts.  Not likely, laws of physics and all that but it can happen.

If the connections between the Thermocouple and the control board are bad (This is fairly common, unplug and re-plug several times)

If the control board is .. shot..  (Sadly my first suspect)

Theory:
Atwood is fond of a single wire ignition/flame sensor set up, In this set up when the T=Stat calls for HEAT, the wire first carries roughly 1,000 volts to the spark gap, which is the end of the thermocouple.. THEN  the control board switches to SENSE mode and looks for just under 1/2 volt, that's a 2,000 to one "hop".

Now.. understand.. If the switch goes wonky and some of that Thousand volts gets through to the half volt sensor chip.. HIstory it is.. and it can no longer sense flame.

Is this the problem.. Well this is only a THEORY. but when my Furnace control board went blotto.. I ordered a Dinosaur Board repalcement (They make one for you too)

First thing I noticed is the price, for the furnace about half what Atwood wanted, for the water heater closer to the same.. Then when it arrived and I looked at it QUALITY jumped out at me.. Nice heavy traces, Well soldered.. Finally Turning over and looking at the component side of the board .. right next to the spot where I suspect that sensor chip is is a neat little Gas Discharge tube.. Now what are those used for on this type of system?

Protection against voltage spikes of course.. The very think I think killed my OEM board.

 

[Martin230]

Thanks for the detail Rene, I fear the board is shot too, although it has only been fired up a few times. Although my question would be how is the system managing to consistently ignite and burn for a few minutes if the board is shot? Diferent  circuit perhaps. And yes the AC side works perfectly but we soon won't  have access to electricity so I'm trying to get the propane part working.

I've also noticed that although the propane side will fire up and burn for a few minutes when cold, it will not ignite if the water is partly heated with the electric heater! I wondered if the ECO sensor was faulty but when I bypassed it the same sequence happened. ...ignite,  burn a few minutes, shut down.

The dinosaur board sounds good, I looked it up and noticed it's not sealed like the atwood one,.....Isn't that a disadvantage considering it's location?  Many thanks again for your input, Martin

 

[John From Detroit]

Question, and you must be OUTSIDE to answer this...

Is it burning for "A few minutes"
or is it burning for a few (like 5) Seconds, then going out, and after a minute re-lighting, and going out, and re-lighting again, and finally going out and the fault light comes on?

This last is what my Furnace did when it failed.. and it is the signature of a failed flame sensor, be it the Rod in the flame, or the chip on the board. OR a bad burn (Clogged burner orifice)  But the chip is #1 on the suspect list for reasons listed in my last post.

 

[Martin230]

Thanks john,

Yes, it burns steadily for about 3 minutes uninterrupted , a good blue flame, a tinge of orange, then shuts down. At that point it tries to reignite a few times without success then the DSI fault light comes on inside and it takes another hour or so to reset and fire up again. Seems odd that it burns so well for a while then something trips it, but apparently not the temperature sensors because when they are bypassed it does the same! It's a good puzzle. Martin 

 

[byrogie]

If you can't get to a service center, call a mobile tech. Most are able to do warranty service.