Water Heater Air Starvation Cutoff (2022 – 811EX SP WB)

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  • #1419
    Charles
    Participant

    Hi All,
    I am writing to see if the group has encountered this. 2022 8-11EX SP, gas water heater.
    The water heater will not light or have a very difficult time staying lit when the exterior panel is closed.

    With the panel closed, and the switch turned on, gas will flow, igniter will spark, and gas will ignite (and a loud bang like an over-charged BBQ grill filled with gas and you toss a match on it). Nothing harmful, really, .. but.. Anyway, the heater will bang but will not stay lit and the system will continuously try to reignite. I experimented with this for several minutes, several times, and I get the same result. Bang. Bang. Bang. Propane fuel ignites but will not stay lit.

    Then open the exterior panel. Re-attempt the water heater ignition. No bang, and first time success and the flame stays lit. Turn it off. Cool it off. Repeat the trial several times. . . exact result. Flip the switch, spark spark spark…. ignition and stay lit. 100% success.

    Then, with a lit water tank heater, I tried to close the exterior panel (careful not to burn hands), and within about 15 seconds the gas burning will struggle (can hear the noise like you are messing with a blow torch) and the sparkler will kick in because it detects a flame going out… that’s what it is supposed to do….. spark spark spark spark…then the flame dies. And then the system will try to restart itself. Gas bleeds, spark spark.. BANG.. ignition! but the flame does not stay lit.

    Then repeat.

    Then, open the exterior panel…. Voila, works again immediately.

    Conclusion: The exterior panel is starving the airflow to the water heat gas burner.

    Looking at the exterior panel there is just the one window (it’s got a wire mesh to keep birds out). That window is serving as hot air exhaust (???) and the same time serving as cold air intake??? Well that obviously causes a problem because trying to feed the gas burner with exhaust hot air depleted of oxygen will starve the flame. I think when the cold air rushing through that mesh window it grabs hot depleted air and within 15-20 seconds the flame starves and dies. Open the panel, problem solved.

    So after my repeated experiment and repeatedly confirmed exact results, question for the group: Are we SUPPOSED to open the exterior panel when we want to use the water heater??? Or if not, how is everyone else’s experience with this? Do you have problem with your gas water heater staying lit? Or? Is it just my unit? Defective? Or ? If the panel can be closed when water heater is operating, then I have a defective unit. Or my exterior panel is missing a SECOND window where cold air is supposed to be fed into the gas burner. Like your car engine’s air intake and exhaust should never mix. This single-window operation seems to be starving the gas burner of oxygen.

    Help please before I start contacting the manufacturer about this. Am I one-off or is this a known issue or I am actually supposed to open the panel each time I want to turn on water heater for hot water…

    Thank you all!!!

    #1420
    Charles
    Participant

    P.S. To the above – This problem existed at the RV Dealership the day I was picking up my 8-11EX. There was no hot water. (Dealer had hooked up shore propane tank). Dealer basically said “well you get the point how the system works you just need to let it heat longer to get hot water…” and moved on. I didn’t think any more of it. It was until I got home and started to setup my 8-11EX for the first trip I discovered this issue–the water heater will not stay lit.

    This explains why we could not get hot water at the dealership–because the heater was not lit. (Dealer turned on the switch and said “ok so let’s give it a few min while it heats up.” See, few minutes later, we still only had cold water. (Didn’t know that heater wasn’t working with the panel closed). And dealer told, basically, we didn’t heat it long enough.

    Now I know. So………… what’s next? What do we do?

    #1424
    Francois Lafontaine
    Participant

    I have been having a similar issue with my 2021 8-11.
    Asked the dealer to check it under warranty but they have been useless.
    Mine often tries multiple times, sometimes with a daily loud explosion. Sometimes the red light inside lights up. Opening the door makes the problem disappear. I have not found a solution. It also smells gas inside when using it.
    Still looking for a solution

    #1436
    S S
    Participant

    Hello NL Friends,
    Not sure if this is the almighty fix, but have any of you adjusted the air to fuel mixture, very simple adjustment. Just loosen the hex bolt holding air adjusting tube and adjust left or right to get a blue flame , now it can be a different adjustment at different altitudes. Unfortunatly not sure if this is your only issue. Now I had to adjust mine because it was surging when lit. Try to get it adjusted to a blue flame( about 1/4 of slot open on tube).
    Really hope this helps!
    SS

    #1439
    Francois Lafontaine
    Participant

    My Water Heater does not appear to have an adjustable airtube (sloted 1/2 inch diameter tube that could can slide left or right). I think the new water heaters from Dometic do not have that. Unless I am misunderstanding your suggestton (I am not an expert)

    #1440
    S S
    Participant

    Francois. I believe after a little research you are correct on the air/fuel mix tube (sliding left to right).
    Sorry for the confusion. My 10/2 NL is a 2020 and that is how I adjust the flame mix. Now looking at a new dometic (picture only) does it not have a small sliding sheet metal area on the fuel tube, ( might slide up-down) to adjust fuel mix?
    Would like to know if it does ,just for my knowledge.
    SS

    #1441
    Francois Lafontaine
    Participant

    Mine does not. I have even disassembled the tube to clean it, nothing to adjust. Maybe I should modify it with a hole and a screw.

    #1442
    S S
    Participant

    Francois,
    Wow thats crazy, not sure why dometic would build units that are not adjustable. Not sure of solution yet. I do like to learn about the newer appliances so I will continue to dive into this issue and relay any info.
    I did look at a new Dometic water heater on line and yes you are correct there is no sliding tube . (Just a quick trick maybe fab up a piece of small metal and place around that opening and see if it helps by choking down opening size, if it helps the maybe fab a new sliding cover and attach it and see if it helps with door closed. I know not much help now ,just has to have a solution.
    SS

    #1443
    Francois Lafontaine
    Participant

    Thanks. Do we need more air or less air with altitude and propane?

    #1444
    Charles
    Participant

    I am writing back to provide update/suggestion but it is still in experimental phase. I wish I can attach a photo (i.e. JPEG) here if anyone knows how, I will try to do so.

    The water heater equipped in this 8-11EX SP WB 2022 indeed has no air mix ratio adjustment. The photo (if I can upload it) will show there’s a black tab next to the Venturi tube and that tab is more of a “block” of something as if to prevent something from getting into the tube. Not sure how to explain its true intended function–nevertheless, for certain it is not for air mixture adjustment. The ratio of gas:air in this appliance is fixed, it looks like.

    My proposal in and experiment in progress (again, wish I can send photo).

    Because propane:oxygen mixing in this type of burner works via Venturi effect, and the Venturi tube (there might be a more technical term for it) is being blocked by the door panel of the appliance (already proven that this problem goes away as soon as the door panel is open), I am building a new door panel with a cut out for air to get in, and installing a louver cover to block water, bugs, debris, etc. In other words, simpler put: build an opening to let air in.

    To do this, I have just obtained an exact replacement door panel for this water heater. I was lucky to find the same color: polar white. Next, I was able to locate and purchased a stainless louver cover plate. I will measure out the dimensions and cut a big hole in the door panel and cover it with the louver. Lastly, to secure the louver cover I will need to drill some holes and secure with hardware. I have not yet determined which hardware, how long the screws, etc.

    I will send link from (e.g. amazon) where I obtained these items. However, before I do, I will do this experiment build for the community and if this absolutely solves the problem I will share (and also share if it is a failure).

    In theory this is the solve. I just used the 8-11EX last weekend, AGAIN, same exact problem: water heater will not ignite with the door panel closed. Then with it open, it ignited the first try and stayed lit even with wind.

    I think the louver design concept will block some of the wind if there is a concern about strong wind blowing out the flame while still provide an opening to allow air into the appliance where the Venturi tube opening is at.

    I will share and report back again, folks. Wish me luck! Thanks all in the Community. We are awesome!

    #1445
    Charles
    Participant

    Regarding High Altitude: Less Propane.

    I fly a small Cessna 172 (not so much nowadays but I still have my license!) and it is our standard procedure to Lean the fuel-air mix every 2,000 ft we climb. As you go up higher in atmosphere, there will be less static air pressure thus less oxygen available to naturally inspired engines and devices. Therefore, as you drive up the mountain and climb in altitude, your naturally inspired burners will pull in less available oxygen the higher you climb, putting this a practical nutshell. Unless of course you have an engine turbine that force feeds air into the burner. 🙂

    So yes, you Lean the propane i.e. reduce the amount of propane at higher altitudes to bring back the proper propane:oxygen ratio.

    Reverse is true, as you drop in altitude you Rich the mixture by adding more propane to the mix to maintain that propane:oxygen ratio.

    Hope this helps. This is how I remembered it, from my Cessna days.
    Climb = Lean

    P.S. (Edit) You need less Propane, and depends on how the adjustment feature is designed, I guess one can either adjust propane or adjust air. True to say you need more air but I don’t know how to adjust the air, I guess opening up more air opening? I’ve always learned to adjust the fuel (in the airplane) because I cannot change the air outside but I can reduce the fuel feed to the engine. Ultimately the result is the same and so doesn’t matter how your appliance adjusts (adjusts propane feed to be less? or adjusts air intake to be more?), as long as you “Lean” at high altitudes you should be able to bring back the proper ratio again.

    Thanks all 🙂

    • This reply was modified 2 weeks, 4 days ago by Charles.
    #1447
    Francois Lafontaine
    Participant

    great, thanks!

    #1448
    S S
    Participant

    Francois, well some info for thought from Charles. He’s right on the lean info, just remember our campers have a fixed jet for fuel amounts so there is really no way to adjust amounts of fuel. Just air ratio. Think like when you go hiking its harder to breathe the higher you climb. So our only adjustment would be air to fuel. Still I’m uncertain at this time how to adjust the newer style Dometic water heaters for air to fuel mix. More digging and or help from a more knowledgable person is in need next.
    Sorry for the long trail of misleading info.
    Gotta be a solution because sounds like you are not the only one with an issue like this.
    I know Dometic now has field reps that are mobile. Another source of info would be to contact NRVTA pretty sharp people there.
    SS

    #1449
    S S
    Participant

    NL Community,
    To me it sounds as if Charles in on to something good related to the air starvation issue. After re-reviewing all the posts, I too think a panel with an adjustable hole might be the trick. (Maybe first try opening panel, and then taping an aluminum sheet metal over area cut at least a 3″ hole around venturi area and then close of hole more and more until results change. This way you know your hole size after testing and not out much in dollars. If it helps then hoorah! Measure hole size and mimic it to original panel with a screen and or adjustable damper for wind or altitude changes.
    Good Thinking Charles!

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