- This topic has 18 replies, 2 voices, and was last updated 3 years, 11 months ago by
.
- Posts
Chris,
Although it is not a common problem, I have seen it a time or two. Normally the back flame means the burner tube is blocked, often by insects or similar. I carried a long Bristol brush on my service truck that I could insert all the way up in the tube to clear it. Looks scary, but usually does not take much to fix nor should it do damage. Amazing sometimes to see how much can accumulate in the tube.
It is unlikely to be a gas pressure issue as when regulators fail they do so to the low side so pressure drops off. Are your other gas appliances working? For example, is the flame on your cooktop burners normal? If the pressure were too high the flame will actually lift off the burners.
Steve
Steve and Andra
2012 F350 6.2 gasser SRW LB
Fab Fours front and rear in case we run into a rhino
2019 Northstar Laredo SCOops, I am assuming here no one got creative in taking things apart and misaligning burner. The loud jet engine like sound also suggests the burner is running air rich. If it has the shuttle that can be turned to cut the air back down, close it some to reduce the roar.
Steve
Steve and Andra
2012 F350 6.2 gasser SRW LB
Fab Fours front and rear in case we run into a rhino
2019 Northstar Laredo SCSo I’ve had it all apart. The burner tube is clear. The main heater tube that goes through the water tank is clear. I’ve blasted it with air and ran my pressure washer thorough at 2500 psi. I had expected to see a mud dobber nest or something to come out. But it is clear.
When I first fired it up from who knows how long it was since it last ran it did the same exact thing. So $200 later for a new main regulator, control valve, pilot, thermocouple, and generous cleaning it has the same symptom.
The stove, LP fridge, and furnace works. In fact, I’m enjoying the furnace as I’m typing this message on my maiden shake down trip sans-hot water.
I also cleaned the jet that comes off the control valve and I made a bracket to drop the pilot deeper in the hole as it seemed a bit more shallow than others.
When I move the air slide as you see in the video it will go from yellow to blue flame but still blows out of the tube at the tank.
Funny thing is I’m 1/2 way to have just bought a new tank with a DSI.
Chris,
Did this water heater work in the pass? The symptoms are not consistent with the parts you replaced and would be more consistent with an orifice someone had drilled out or an orificie that is the wrong size, or a flame tube that is misaligned so the gas does not go straight down the tube, etc.
It would have been possible to check the pressure at the orifice, although that was never likely to be the problem.
If the water heater looked just like it does in your video when you first fired it up, it is obvious that it has been taken apart (no insult intended).
The orifice is in place in the orifice holder right? The orifice is that little brass piece that can be screwed out. Just shooting in the dark here as there has to be a very simple answer to this problem and I have seen units where the orifice was lost. Not crossed threaded. That is the single piece that controls the gas flow at a given pressure and since everything else is working as normal, you have reason is believe the pressure is good.
Steve
Steve and Andra
2012 F350 6.2 gasser SRW LB
Fab Fours front and rear in case we run into a rhino
2019 Northstar Laredo SCSteve,
Thank you. This is the dialog I need to figure this out. No offense taken. In that video was after I had pulled the pilot assembly on and off several times. And just hung it back to test again. I don’t know the history of the camper. I bought it from a guy that got it from the Chevy dealer where the prior owner traded it in with a truck. Likely because a Jack was broke and he couldn’t get it off. That’s another story.
But when I filled the LP for the first time and leaked checked, I also filled the water tank with water and tested. It did the same thing then. No video.
Thus I cleaned everything. Removed the unit from the rv and reinstalled with a new regulator, control valve, pilot, and thermocouple. I removed and cleaned the orifice and that jet tip. It unscrews and screws in smooth. I don’t know if anybody upsize drilled it or not and don’t know how to check.
I tried replacing the burn tube. Got a new one based on the serial number. It came in way too short. Don’t know if they mispackaged or if that is part of the issue. I have to call them back about that tomorrow.
Ugh. Has to be a simple solution. Oh, and I will have it all super tidy and neat and like new looking if I can get this to go.
Hi chris,
I guess there is always a first time, but normally water heaters are so basic they are boring to repair. When I was diagnosing, I always broke the system into parts. Since you have an overflame condition, it suggests a misalignment or an overpressure possibility. As I said earlier, the manufacturers all design their components to fail to the low pressure side and in 30 years I never one time saw an over pressure condition from the regulator, but I guess anything could be possible.
I would start with manometer at the cooktop to verify pressure from the regulator at the tanks. You start there because it is super easy to hook a manometer to one of the burner spigots. If pressure there is correct, 10-14″ water column, it should be good through the whole system in that there is no way for it to be too high anywhere if it is not too high there.
Next, check for the correct orifice. This is not a common issue, however one thing that always amazed me was how often folks thought the problem was not enough gas so they drilled out the orifice. There should be a number stamped on the orifice and you can find the correct orifice number online. They are cheap and easy to swap in a new one.
If the pressure is good and the orifice is good, it is a burner issue and I can’t tell you more about sorting that one out as has to be a mechanical issue i.e. alignment, etc.. If you were close, I would say just bring it by the house. Diagnosing at a distance is hard, hands on is usually much simpler.
As you likely discovered the service manual for this water heater is online and is the same one I used for years http://waterheatertimer.org/pdf/Atwood-Water-Heater-Service-manual.pdf
Steve
Steve and Andra
2012 F350 6.2 gasser SRW LB
Fab Fours front and rear in case we run into a rhino
2019 Northstar Laredo SCChris,
It is only infrequently that I lie awake in bed puzzling over an RV appliance, but there I was last night running through this in my head.
Here is the question I can not get around. Why is the flame not extending up into the heat exchanger? That tube runs up through the water heater tank and vents out and the flame normally goes right up the tube. That flame looks like it is hitting a wall. I just don’t get it, can’t even figure out how it is possible!
Steve
Steve and Andra
2012 F350 6.2 gasser SRW LB
Fab Fours front and rear in case we run into a rhino
2019 Northstar Laredo SCChris,
It is only infrequently that I lie awake in bed puzzling over an RV appliance, but there I was last night running through this in my head.
Here is the question I can not get around. Why is the flame not extending up into the heat exchanger? That tube runs up through the water heater tank and vents out and the flame normally goes right up the tube. That flame looks like it is hitting a wall. I just don’t get it, can’t even figure out how it is possible!
Steve
That’s often when I solve my biggest puzzles! I took my propane torch from the shop and stuck it into the heater tube hole and lit it up – it burns normal and blows the flame right into the tube. I was hoping it was going to act like it was hitting an obstructions…but no.
So, I called the appliance parts house this morning and gave the serial number again and asked them to double check the burner tube they sent (as it is too short to even try) and to see if they have the correct orifice jet for that application. She said she will call me back.
To check pressure at the cooktop, remove a burner and that leaves the spud that the knob controls. The manometer I have came with an adapter that slips right on the spud so all that is necessary is to slip it on and turn on the burner.
If you don’t have that adapter with your, but you have the brass adapters, you can also check using the test port right on the gas valve. The service manual pictures its location.
Steve and Andra
2012 F350 6.2 gasser SRW LB
Fab Fours front and rear in case we run into a rhino
2019 Northstar Laredo SCExcellent. I’ll go over that this weekend when I have some more time. The RV appliance folks are re-sending what we hope is the correct new burner tube…and they have an orifice jet on order for me – they tried but couldn’t find any in-stock in the area. That covers all the parts I can replace and is likely good insurance to do it anyway so I’m at a pure baseline no matter what.
I pulled the cook top off and realized…it is the ONE area I didn’t do a deep clean on this camper! YIKES! Anyway, that is now handled.
I went ahead and installed the new burner tube. No difference. I’m starting to question if the fitting that comes out of the bottom of the valve is the correct one. This is the fitting the jet goes into – and I’m waiting on the new jet. It seem too short – and the burner tube is barely able to reach – but it does reach.
- Does any body have a picture of the fitting that should be coming out of the Robertshaw control valve?
Remember, mine had the other valve to start with, and when I ordered a new one it mapped over to the Robertshaw. Also, this is the SAME symptom it had with the other control valve. Either could be present on this model. I like the Robershaw better the way it adjusts and lights.
Chris, As I said earlier I am out of ideas without being there. I never found the type of valve made any difference and it still sounds to me like your heater is running with way too much air in the mix given the jet engine sound.
Steve
Steve and Andra
2012 F350 6.2 gasser SRW LB
Fab Fours front and rear in case we run into a rhino
2019 Northstar Laredo SCI give up. Everything checks out. As far as I can tell. And while dorking around with the new jet and burner tube I broke the gas line to the pilot. Ugh.
Thinking I should cut my losses and just order a new water heater. It is beyond me.
By the way. Before breaking the gas feed tube I got the main jet aligned like a pro. It fits and slides and aligns perfectly. Light it up and still getting the blow out flame.
Anybody want some barely used new parts????
No updates…been distracted with other year end projects. I’m just going to replace the water heater complete. I have a working theory – that it is possible water was left in the water tank and maybe it expanded into the heat tube area just out of site – not enough to crack and leak. Maybe it just won’t flow the air right no matter what I do. So confused. Would be funny if this whole thing was a problem with my propane tank valve. I have a new pressure regulator, but the tank is OLD. While the local gas company certified it…I noticed it now leaks a bit of gas when opening and closing the valve – which I did a lot of during testing of this unit. Once I run the tank down a little more I’ll take it back and they say they can put a new valve in it for me. It does NOT leak anything at full open or full closed (I’ve checked each time I’ve cycled it).
- You must be logged in to reply to this topic.
