View Full Version : Optimus Crux Stove and the Mysterious Flame
Hey folks.
Just got my first backpacking stove--an Optimus Crux. I ordered it online and the outside box showed up totally crushed. (All good, customer service said i have a year to return if there's an issue.) Tried it out yesterday and noticed that my flame kept going out. (It wasn't windy.) I plan on making a windscreen for it this week and trying it out again with the screen. However, my question is this--should I be concerned? Do flames on these stoves usually go out that easily? My gut feeling is that this is just a windscreen issue and I plan to play around with it some more. My only past experience is with a huge Coleman double burner camp stove with a windscreen, and that thing works like a ten pound charm. Thanks.
capehiker
10-16-2016, 13:13
I never use a windscreen and only get a flameout in real windy conditions with the Crux. Also- be advised a windscreen for a canister stove is placed different than for an alcohol stove, but you shouldn't need a windscreen if there's no wind. Those stoves put out a good force of flame.
SWODaddy
10-16-2016, 15:45
I think the issue is that the crux has such a large burner that it's sensitive to fuel canister pressure changes. I like the flame a lot, but you have to babysit it at low power.
Thanks for the tip, Capehiker.
After reading your comment, I went out and tried it again and realized my mistake. I believe I had the valve opened minimally during my initial test run in order to control the flame and possibly not enough gas was coming out which may have impacted on the flame. Tried it again--same conditions (although slightly more wind today) and opened it a lot more. Had this thing roaring, water boiled in less than three minutes. Looks like success is mine. Thanks again.
I think the issue is that the crux has such a large burner that it's sensitive to fuel canister pressure changes. I like the flame a lot, but you have to babysit it at low power.
That's exactly what I didn't realize my first few times with it yesterday--I had it waaaaay too low. Moments like these I'm glad to take the time to test this stuff before taking it out.
Rain Man
10-16-2016, 17:31
I returned mine because of this problem.
poolskaterx
10-25-2016, 18:53
I've been using my crux for about 3 years now. Turning it way down can be tricky but with practice you can get a very low flame to simmer or just keep things warm. In heavy wind I like to make a wind break to keep the flame from blowing out and also to keep the heat more concentrated on my pot. I am always impressed with the speed that this stove will boil my water or melt snow.
ScareBear
10-27-2016, 08:44
The Crux and CruxLite need to be started with the gas at 1/2 pressure or better. You need to increase the flow as the burner warms up to maintain steady pressure. There isn't anything wrong with your stove...
ScareBear
10-27-2016, 08:45
I meant to say 1/2 of full pressure flow, not 1/2 full canister....sorry...
Rain Man
10-27-2016, 22:50
You need to increase the flow as the burner warms up to maintain steady pressure. There isn't anything wrong with your stove...
To me, that is the definition of something wrong with the stove, if it won't hold a steady burn on its own.
SWODaddy
10-28-2016, 08:25
To me, that is the definition of something wrong with the stove, if it won't hold a steady burn on its own.
The problem is the best feature: The huge burner. You're trading a nice, even heat distribution in exchange for fuel pressure sensitivity.
For me, the positives outweigh the negatives because I can actually cook with this burner using titanium cookware, whereas something like a pocket rocket will just scorch the center. That it folds flat into the bottom of a fuel canister is also a huge plus.
ScareBear
11-11-2016, 10:15
It's not a "problem". It is physics at work. The design of the burner provides for a wonderful flame that is infinitely adjustable, once warmed up. It needs to be warmed up to compensate for the enlargement of the burner by thermal expansion which actually reduces the visible flame because there is actually MORE gas leaving the burner while the flow remains constant, as it warms up. Thus, you increase the flow of gas through the burner during the warm up to compensate. The end result is a fully responsive burner with a fully adjustable flame that is evenly spread across the bottom of any surface. It's design also eliminates flare ups and "pops". It is a well-regarded product, and as mentioned above, the CruxLite folds into itself and neatly stows underneath your fuel can with then stows in your cookpot for an ultra compact and ultra light weight solution to cooking. I am waiting for a detached canister Crux model to come out so the you can invert the can for winter cooking. Of course, YMMV....
Rain Man
11-11-2016, 12:17
I suppose I just have to chuckle at the proposition that this stove's obvious defect is really a "feature" or in some alternative is user error.
In fact, if this stove requires a warm-up period and then works just fine, that's news to me as I have let mine warm up indoors and out and have adjusted it regularly and it still goes out or down to next-to-nothing.
Besides which, if this is a requirement, and if it's not a defect in the stove itself, then it is a defect in the owner's manual which says no such thing about any such requirement. I'm holding the tiny little manual in my hands right now.
Googling this stove and this problem makes it obvious this is a defect many users are commonly experiencing. It's like a car recall. After a while, the manufacturer can no longer claim it's isolated incidents or operator error. It's a manufacturing or design defect. In the law, there's a Latin term, res ipsa loquitur. The thing speaks for itself.
As with car recalls, the fact that some such cars don't blow up is not proof that there's no defect in that model of cars. In fact, the opposite is true. A critical mass of consumers suffering the same problem with the same product proves there is a defect with the product, even if all haven't had it fail ... yet.
ScareBear
11-12-2016, 10:22
Well, just return yours, then. Everyone I know that has one loves it. My only complaint is that because the burner is so large and the flame so wide, it is a bit wind sensitive. I had to add a windscreen. Your experience has differed. I googled "crux lite flame problem" and didn't come up with anything at all. I've used all kinds of stoves over the last 40 years. I choose to backpack the AT with my CruxLite, "problems" and all. My stove is vital and I wouldn't hike with one that didn't work exactly as I wanted and was 100 percent reliable. Your mileage may vary.
J.K. Rowling is at work on another series of books, this time set in the world of backpacking, and the main character is named "Optimus Crux." The title of the first book is going to be "Optimus Crux and the Mysterious Flame." Optimus Crux has his quirks and tends to be a slow starter but is at his best once he gets warmed up.
(I've been wanting to post this for the last four weeks, since I first saw the title of this thread, but waited for fear that thread drift would prevent becfoot from getting helpful answers to the stove question. It's been really hard to wait four weeks.)