This is a review of the Butteryfly Kerosene Pressure Stove #2412 that I recently bought. It is a “Primus Type” stove in the pattern of the original designed in about 1892.
There’s a wiki about the original:
That has a pretty good image of “the original” that my stove does as a “knock off”.
The Butterfly makes a couple of improvements on this basic design, but is basically true to the original design. First off, the burner assembly screws on / off of the tank. There is a nut supplied that closes off the fuel tank when the burner assembly is removed. When in use, they thoughtfully provided a set of threads on the pump handle. The nut screws onto that for ‘safe keeping’ and becomes a nice pump knob.
This makes the butterfly ‘portable’ and also means you can fully seal the fuel tank. The original was always open to the burner, so if transported, it could leak. If the fuel tank vent was closed, changes of temperature would pressurize the tank and cause kerosene to leak out of the burner. The Butterfly lets you seal the tank completely. Nice.
All this makes it sound like a small backpack stove. While it can fit in a pack, it isn’t small. Here is a picture of the stove with a large pot, about 8 inch diameter, on it. The pot bottom says it is a 3 quart pot. In frame are some other objects for comparison. A 1 cup measuring cup (showing the 250 ml side) in the foreground. A one pint Guinness glass and 325 ml MSR red fuel bottle to the other side. Toaster in the background. This is serous stove and can handle a real pot. Not just a dinky ‘trail cup’.
It also came with little rubber feet so is kind to counter top surfaces. It isn’t clear if the Original ever had feet. They would likely have decayed by now, if any kind of rubber.
I ordered the stove directly from the vendor. It is also sold through Amazon, but didn’t see why giving them a ‘cut’ of the action was of benefit.
Since it said “Ships from and sold by St. Paul Mercantile. ” A couple of online reviews said St. Paul Mercantile were good folks with good service, so I decided to just order direct. The product arrived 8 days later, per the order date and UPS notification of delivery. The online order was simple and easy and about the same as Amazon.
When the package arrived, it was the original box inside a shipping carton that was an exact fit. All parts were present and everything looked fine. I assembled the stove and did a test burn. Assembly was easy and everything worked ‘first time’. One small issue
was that the included wrench didn’t fit [ See the Update. It fits, but the next nut higher up between burner head and riser tube, not where you would expect.] but just putting the burner assembly on ‘finger tight’ was fine. ( I have strong fingers ;-)
UPDATE #2 on 11 March 2013
Down in comments, John, from St. Paul Mercantile, explains that the burner assembly is to be installed without a wrench. The burner head (or just ‘burner’) joins to the stem pipe with the nut that this wrench fits. The wrench is not for installing the burner assembly (of burner head and stem) to the stove; only for tightening the burner head to the pipe stem. (I presume you find your own wrench for the other nut when doing that tightening).
So, as I speculated in my first update (down below), it is a “feature” in that it discourages using the wrench to install the burner assembly. ( I have also added the word “assembly” in some key places to help make clear that the “burner” isn’t the “burner assembly” that comes already assembled in the box and ready to screw onto the stove by hand.)
That all makes the following picture an amusing testimonial to my ability to “leap to conclusions” and “not follow directions well”, more than any “issue” with the stove or tool. With that, back to the original posting:
Not a big deal. I did a ‘test fit’ with a couple of metric wrenches. A 17 mm is too small and a 19 fits, but is a bit loose. Either the nut is an 18 mm (the 19 mm did not feel that loose) or it is something “English” from the original design why back when and the wrench is a metric “almost right”. When I can find my English / SAE wrenches I’ll see if one of them is the right size.
As it stands, it looks like the nut size may be a bit off. What is clear is that the stamped steel wrench is useless. (No, the wrench is right for the intended use. I was just trying to put it on the wrong nut. It goes on the burner head where it joins to the riser stem, not to the bolt at the bottom of the burner assembly.)
UPDATE 10 March 2013
I thought about it and realized there is a second ‘nut’ on the burner, just above the “spirit cup”. The wrench does fit that nut. Why the other nut is “almost the same but not quite” is an interesting question, but at least the wrench can be used at that point on the stove.
Frankly, I’d much rather do the “on and off” at the nut closest to the tank (not sending torque through the burner head /stem joint and risking removing the burner head from the stem). In reality, best would be to do “on” at the ‘burner above the stem” nut and “off” at the “nut nearest the tank” (always tightening the burner head / stem joint) but the two nuts are not the same size.
I suppose this might be seen as some kind of “feature”, but I can’t figure out how. (Update2: “How” is that it prevents applying the wrench to that nut to install the burner assembly to the tank; when the wrench is for doing maintenance on the burner head to stem joint. i.e. tightening it if it gets loose.)
At any rate, that answers the question about the ‘nut vs wrench’. As it fits the upper nut, the wrench is sized correctly for some size nut. So it is a non-match between the two nuts that is the source of the “issue”. Left open is the question of “is this a ‘feature’ that is poorly documented in the instructions, or is it a non-spec nut at the bottom of the stem?” (Update2: It is a poorly documented ‘feature’ – or I’m just not good at paying attention to “burner” vs “burner assembly” in directions.)
Back At The Stove
Note that the original stove is called a ‘spirit’ burner. I just ran mine on “Odorless Mineral Spirits” that in the USA are a kind of light kerosene. I suspect it would run on most anything from gasoline to Diesel (as another site claims) but that using gasoline is a bit risky… The tank warms in use and you reduce power by opening a vent to vent vapor / pressure from the fuel tank. Not risky with kerosene; but on gasoline? I’d only try it if in a genuine emergency. There are online sites that state they have run the stove on Diesel and other fuels. The manufacturer says Kerosene. My evaluation is that it would likely work well on other oil like fuels, and even some more exotic fuels like alcohols or naphtha, but with potential risks for the high volatility fuels that are unwarranted unless in a real emergency.
The stove works fine with very little odor at all. I don’t know if it will have more smell on ‘real kerosene’, but I don’t expect much. The way the burner works, at relatively low pressure, and with no valve, means that you shut it off by releasing the air pressure in the tank. Any fuel in the “stem” drains back to the tank and what is left in the burner evaporates and burns, then the flame goes out.
During the assembly, I had run the burner first, then decided to put the pot stand in place. I did this while the stove was running. That was a mistake. While it looked “easy” and just “drop the legs into the bottom pipes”, there was some kind of small burr either on the ends of the legs or inside the holes they entered. The legs slightly ‘hung up’ on insertion. It took some pressure to get them to seat. Then, when time to take the stove apart, it took a bit of ‘persuasion’ to get them back out again. A ‘test fit’ with each leg, twisting with a ‘reaming’ motion, would have removed the burr and made the whole process easier. There is also a slight “splaying” force on the legs when installed. I take this to be a ‘feature’ as it helps keep the burner in place. It would have been nice to discover that without the flame running. So “My bad”. After the first assembly, subsequent assembly was much easier. (Whatever bit of metal was ‘tight’ has been worked down enough to be ‘snug’ instead.)
OK, there was only one issue that was significant.
The Burner Flame is Off Center
There is a defect in the burner assembly. It is designed such that a jet of kerosene vapor squirts toward the bottom side of the end of the burner, that then spreads it out sideways (while warming the fresh kerosene inside that burner head). If the vapor jet squirts slightly off to the side, the whole flame is off to the side. Here’s a picture of the flame, straight down from above.
That flame is OK in an ’emergency stove’, for ‘just need something to cook, anything will do’; but it is not going to give even cooking. Here’s a picture of an 8 inch pot showing that the water is boiling right over the large flame spot, but not evenly around the pot.
To the credit of this stove, it could get that water to the boil without a lid on the pot. Some camp stoves I’ve tested can’t do that in a pot with that much open surface area. A lot of water evaporates as steam taking heat with it. The stove was not pumped up to full power, either. It was at ‘pretty good’. Sound level was about the same as an old Coleman 2 burner gasoline stove on high. Maybe a bit louder. The Coleman single burner 533 Dual Fuel is significantly quieter. In my test boil of 1 pint of water, the 533 Dual Fuel boiled in under 4 minutes, this Butterfly stove in about 10 (but I think much of that was due to the off center flame on the small 1 pint pot not evenly heating all sides).
I intend to buy the “Quiet Burner”, but it isn’t really needed unless you will use this stove as a regular kitchen appliance. I had wanted to order the “Quiet Burner” option, but could not find it on their web site. I was going to order the stove, and that burner as a ‘spare’ and maybe a parts / repair / emergency kit; but being unable to find that “Quiet Burner” listed, decided to just see if I could order the ‘full parts kit’ with that burner via a phone call to the order desk. Now that this burner is defective, all that goes “on hold” while I figure out what to do and contact customer service… The “full spares kit” has a second regular burner in it and comes with washers, gaskets, pump parts the works. It’s about $32 and a “spare burner” alone is about $20, so I presume the “Quiet Burner” is similar. All up that’s over $50 and getting close to the price of a whole stove. I don’t know if the “spare parts kit” can be ordered with the “Quiet Burner” as an option, or if I end up buying 2 burners. Then there’s the risk that this is part of a batch of ‘bad burners’, so not wanting to double my money “in” to get 2 more that are ‘not quite right’… It’s easier to just say ‘OK, it’s not a daily use stove, it goes to the “hell, it’s an emergency… anything that makes fire is welcome” kit/pile’. But we will see what happens after “Adventures In Customer Service Land”. When I get a good burner for it, this may well become a ‘daily driver’ of a stove.
OK, a couple of more quick pictures. Here’s the pot ring shown from below. You can see two things here. First off, it is a bit of stamped sheet metal. The original looks a bit more like a casting. So this is lighter, but seemed to work OK. Second, you can see how the ‘off center flame’ has caused off center heat / scorch marks. Don’t know if that’s a bad thing, or not. It’s not very cosmetic, but I don’t know if sending more heat to one side overheats (and weakens?) that side.
If you look at the 2 o’clock, 6 o’clock, and 11 o’clock (more or less) positions, you will see the little bent over tabs that the ends of the legs go into. The “L” end goes into those from the outside, then the long leg goes into the little pipes on the side of the fuel tank. Not hard, really, once the long leg ends have had a trial fit / polish.
I love the brass finish of the stove, BTW. The general “fit and finish” of the fuel tank and pump is great. I get the impression that the “new guy” is assigned the legs and such. Inspection of the burner assembly looks like heavy duty copper / bronze and not something where I can just bend the jet into alignment. It looks like the jet screws into a threaded section that is braised / welded onto the center pipe and that the joint there is slightly out of alignment. Attempting to ‘realign’ that by bending is likely to break the weld joint.
I’m not real proud of this next picture. I had to apply extra side light and used my Maglight with the LED bulb. It has a slightly blue light, so we have some blue mixed with incandescent overall lighting. I also could not get my small camera to focus well in this shot. If needed, I can do a ‘re-shoot’ under daylight with the big camera, but I think this shows what is needed. OK, it’s not a Rembrandt… Here we are looking at the bottom side of the burner head. You can see from the soot pattern that the jet of kerosene gas is hitting well off center. (The jet is that blurry dangly bit in the middle of the inner top arch) One side has lots of soot, the other nearly none. The jet ought to be hitting near dead center with more or less symmetrical soot.
The stove is made in Indonesia, but a bit of searching showed the
parent company Distributor is in Singapore. It’s a Chinese run company, near as I can tell. In general, the build quality is good. Yet marred by cutting just one or two corners too many. That is a common theme from Chinese companies. Sigh. I wish they would learn that with just a tiny bit more effort on quality inspection and systems (and caring about quality, really) they could make consistently great products with not a significant cost increase.
Looking around, I found several makers in India that produce a similar stove. None imported to the USA near as I can tell. With “per piece” prices of around $10 to $20 (for various stoves like this one, and even some not like this one) I’m tempted to go into the import business… but with the minimum order typically being “one shipping container”, I’d need to find about $50,000 just to place an opening ante. (Wonder if the wife would let me put a second mortgage on the house? ;-) For that, one needs to know what the quality is before making the order. Yet in India, these are the typical “big purchase” for poor rural folks. Not something where they will spend a couple of weeks wages and accept “not quite right”, I suspect. They also have 4 different sizes. But a canvass of local Indian stores showed none for sale here, and an online search showed only one vendor of this kind of stoves. It’s pretty much “Butterfly or nothing” for a “Primus Type” stove in the USA. At least for new ones.
I’m hopeful that this is just a ‘one bad burner’ issue and that “Customer Service” will make it right. Every product has a few that don’t arrive right, so I’d not hold that against them. A visual inspection of the burner would be hard pressed to find that alignment issue. (A ‘test jig’ would). Yet that does not lend confidence. IFF their QA process can’t catch a bad burner alignment, what’s to say one station doesn’t have a ‘bad jig’ and just keeps turning them out forever? Or that “the new guy” will be making bad ones for a few months while he learns? So I’m not looking forward to playing “Burner Roulette” and finding out how many burners in a row can show up ‘not quite right’. Also not looking forward to “who knows how much time” at the UPS store doing “Ping Pong Shipping”… a series of “ship that one back and we’ll send another” gets old fast. Oh Well. “It is what it is”.
That aside: I generally like this stove more than my Coleman Dual Fuel. The size is too large for light backpacking, but a very nice size for kitchen use. The largest pot I typically use (unless making a major pot of chili…) fits just fine, and I suspect the Major Chili pot would fit too. It would be fine for “car camping”, IMHO. The brass is a joy to look at. The thing is easy to use. Priming is simple (pour methanol into cup. Light.) At about 80% gone, close the vent on the fuel cap, and slowly start to pump. When the kerosene starts to burn, stop pumping until all the methanol is gone. Then pump to whatever power you need. It takes far less pumping than the Coleman and it is just more gentle about it. The needle valve that vents air from the tank to drop power works very nicely. Fine control is possible. The sound level at modest power settings is about like an old Coleman gas stove on high. If really pumped up, it makes a bit more noise, but quite livable. I think with the “Quiet Burner” option it would be easy to live with on a day to day basis.
It heated water for tea nicely, even in a very broad and uncovered pot. With a lid and at power, I think it would be quite fast.
All in all, I like the stove. I’d likely buy another one if I thought it was going to arrive in good order and with all parts working right. As it stands, I’m pondering what other options might exist. As an “emergency stove” it is fine. As a ‘daily driver’, I’d want a proper burner, and likely the “Quiet Burner”. Once done with “Customer Service”, I may yet buy the parts kit and the “Quiet Burner” as an upgrade. For now, I’m making my daily tea on an alcohol stove instead. Not as much fun as this one (no moving parts, and no whooshing sound of power ;-) Also a bit slow… but that’s alcohol for you ;-) In a few weeks, assuming I get an even burner, I’m going to try doing some frying and even a largish pot of beans on it. Two things that are hard to do on smaller stoves. Frying needs even heat, and a pot of beans needs long duration heat after a high power start. Neither usually goes well on small stoves. Somehow I think this stove is ‘up to it’
Oh, and one “hint”: I was resenting a little bit all the fuel value being burned up in the alcohol cup just to warm up the stove. Then I realized (in a “Doh! Moment”) that nothing at all prevented me from setting a pot on top of the stove while the preheat was happening. Heck, it would even help trap the heat near the burner. Also, I filled the cup to the top. At about 3/4 burned, decided to test the kerosene so closed the vent and Very Slowly started to pump just a little. The kerosene vapor started adding to flame immediately, but was a bit ‘billowy’ from the methanol flame disrupting air flow. It looks like you don’t need a full cup of pre-heat when starting from room temperature. I’m going to try 3/4 full next time, then iterate which ever way is needed. In short, the stove warms fast and you don’t need a full cup of preheat fuel; even with that, the ‘start to cook’ can be as soon as you light the alcohol on fire…
Finally: The stove just looks nice. It has writing on it in English that says Butterfly and another script that is a bit exotic. It might be Arabic or it might be something Indonesian. It is highly stylized to hard to say for a non-speaker of whatever it is. But in any case it has an esthetic to it that just oozes “expedition to exotic places”. It’s pretty, and reminiscent of “other times” and “far away lands” in a way that just doesn’t exist anymore in most products. Frankly, I just like the darned thing. In a world of stamped steel and plastic knobs with tiny stoves on hoses to aluminum fuel bottles advertizing some name in bold paint, it is just kind of elegant. I like that.