Water heater flame discharge

[SummitPond]

I have an Atwood GC6AA-10E water heater. I normally use the electric element to heat water, but this weekend I wanted the hot water quickly so I used the gas. Lo and behold, I had no hot water when I checked a while later. After that, it wouldn't even heat up with the electric element. I determine the thermal cutoff was the issue and replaced it. It now works on electricity. Then I tried gas. Flames spewed forth from the main burner tube (you can see the bottom center of the label that is in the upper right of the photo is singed - must have occurred the first time I turned it on with the gas; now I see why the thermal cutoff blew/tripped). I assume there is a blockage in the main burner tube.

Question: How do you go about removing the main burner tube so it can be checked and cleaned (I assume it is the tube that goes into that large round hole)? The service manual I have doesn't provide details - it just says "do it". What other issues might be causing this issue?

Thanks in advance for your help.

[Thundershorts]

You could have a couple of issues. There could be a blockage in the burner tube or orifice, insects are attracted to these areas and you may get spider webs in there. I the flame is rolling out, there could be a blockage in the combustion chamber or the flue chamber.
From what I see on the internet, in order to remove the burner assembly, it looks like you may have to remove the gas valve and a few other screws. I have no idea how a person would check for a blockage in the flue chamber on an RV water heater, as it runs through the middle of the tank and is curved. You can see if the flue gasses are coming out of the exhaust, and this will give you an idea if there is a blockage in there or not. You can hold your hand near the exhaust or hold a mirror near it, the mirror will fog up.
Chuckster may be able to help you out some more.

[chuckster57]

1/4" screws hold the burner tube assembly on. The one at the gas valve is a threaded screw, the rest are sheet metal screws.

Unplug the sparker from the board, then start taking out the screws. One above the burner tube (usually a self tapping screw) and then the sheet metal screws, one right below the E.C.O. And the other underneath in the same area. Then the threaded one on the gas valve assembly.

Once the burner tube is off, inspection is easy. Common for spiders to set webs. Can't say I've ever seen the "heating" tube plugged.

Once your done and put it back together, you can adjust the flame by moving the slotted part to regulate the amount of air. You want a STRONG flame.

[SummitPond]

Chuckster, Thank you for the detailed instructions.

Thundershorts, Thank you for your feedback, too.

I will "attack" it this weekend and hopefully remedy the problem.

[SummitPond]

Got it done in about 20 minutes following Chuckster's instructions. That's amazingly fast for me!

Lesson learned. Don't just throw the gas HWH switch and assume all is well. Drop the panel and ensure the flame doesn't come roaring out. Thundershorts and Chuckster were right - there was a fine (but thick) spiderweb (almost cocoon-like) across the middle of the tube; difficult to get to, too! Thank you both again.

I've attached some photos of the pieces/parts for those looking to do something similar in the future.

1) "assembled" - the water heater as found (I have already disconnected the spark igniter from the control board)
2) "heater w/o burner" - after removal of the heater tube assembly
3) "burner tube attached ..." - bottom shot of burner tube and frame assembly showing the two screws that hold the flame spreader and the burner tube to the frame assembly
4) "burner tube frame ..." - showing the frame assembly and spark igniter after the burner tube has been removed
5) "pieces/parts" - the burner tube, flame spreader and airflow adjuster

[PARAPTOR]

ShacterShack, Good Job!! and (ty) for the detailed followup