Mar 9, 2013 at 4:18 pm #1300246
I bought Crown's "green" denatured alcohol and put a little in my bottlestove tonight to try it out for the first time. Here's the result.
Air temp was around 65*, no wind, water was from the faucet (on cold). This is pretty much what I would assume in the summer here in the southeast…if not warmer.
The pot is a BPL Ti 1100 ml w/ lid, 4.5" in diameter. The windscreen is Ti from QiWiz.
I had 3 cups of water boiling in about 5:30.
From these pictures, can you guys tell me if I am going to notice much in terms of efficiency if I get a wider pot? The flames are definitely spilling over the side.
BTW – I might be hooked. That was cool! Big thanks to QiWiz for his help and for two great products!Mar 9, 2013 at 4:25 pm #1963590
@funnymoLocale: Sunshine State
Judging from the pics, a wider pot would almost certainly yield better efficiency.
That said, your boil time for 3 cups beats most alchy stoves' 2 cup performance! Wow, that is really great performance. Which stove are you using?Mar 9, 2013 at 4:36 pm #1963591
I am using a bottlestove bought from Qiwiz
How wide of a pot should I get for this stove?Mar 9, 2013 at 5:21 pm #1963612
@jonfongLocale: FLAT CAT GEAR
Since you bought the stove and windscreen from QiWiz, you should probably ask him directly.Mar 9, 2013 at 5:24 pm #1963616
The flames look very yellow. This might indicate not enough air for the fuel to burn completely. I can't tell from your photos but you should have some way for air to get in at the base of the wind screen. Many people add a row of holes near the bottom edge to insure good air flow.
The flames on your stove are very pig and your boil time seems fast. If your wind screen doesn't have any air intake holes your stove might get very hot which would accelerate the fuel burn off and would produce larger flames. Your stove would be more efficent with a slower fuel burn rate.Mar 9, 2013 at 5:28 pm #1963618
The windscreen from QiWiz has holes in the bottom. That's good information…thanks! I'll talk with him and see what he thinks.Mar 9, 2013 at 5:30 pm #1963620
@acrosomeLocale: Back in the Front Range
@ "That said, your boil time for 3 cups beats most alchy stoves' 2 cup performance!"
Yes, the TIME beat most other stoves. But how much fuel was consumed? Because that's how you get an alky stove to beat a canister stove on weight- you need decent fuel efficiency. With that quick a boil time I'll almost guarantee that he burned a ton of fuel.
I've done a fair bit of comparison recently, and that seems to be the trade-off: Faster boil times consume more fuel. He needs to fiddle with letting more or less air get through the windscreen, and the height of the pot above the stove, and see which nets the efficiency/time tradeoff that he prefers.
Clearly, though, yes, the low-hanging fruit right now is a wider pot. Or, actually, maybe a taller windscreen- in the house that tall jet of flame up the side of the pot probably worked well, but in even the slightest breeze it won't. Also, I have to wonder if those flames burn so high because of all the air they're getting? Maybe a higher windscreen would lead to the stove burning leaner, and thus a longer boil time but better efficiency.
Do you have a scale? The easiest way to measure fuel usage is to weight the filled stove before boiling, and snuff it and weight it afterwards and do a little subtraction.Mar 9, 2013 at 5:38 pm #1963627
I have no idea how much fuel I put in there, but the stove went out about 20 second after the boil started. Inside the stove, it wasn't more than 1/3" deep…bear with my guestimation as I don't have a means of measuring fuel at the moment.
I'll tinker with raising the windscreen to see if I can get better airflow underneath. Raising the pot, at least on this stove, seems counterproductive since the pot blocks the main opening from burning and pushes the flame to the outer holes/jets.
Take all of what I say with a grain of salt. I have only used this stove once…and it's my first.Mar 9, 2013 at 5:45 pm #1963631
Oh and what's the best way to pour the alcohol out of the stock container? I'm going to get a small bottle soon…but even still, I'll need some tips. My first pour was a big spill.Mar 9, 2013 at 5:47 pm #1963632
@slammerLocale: Oklahoma Flat Lands
Tyler I hope you know "alcohol" is addictive!
You will start thing about different designs a work then you'll wake up at 2:00 A.M with an improvement.
Ya you'll be addicted!
As far as measuring -(if you have) use one of the kids liquid medicine measuring cups most have milliliter incrementsMar 9, 2013 at 5:48 pm #1963634
It is really nice to be able to pick a pot up while the flame is burning.
That is the #1 drawback of having flames engulf your pot, may need to wait for the stove to burn out. Even so, an attached handle may then be too hot to use.
There is no reason to be in a big rush to boil water, efficiency is #1 goal.Mar 9, 2013 at 5:48 pm #1963635
@newtonLocale: Southeastern Louisiana
IME I have learned that alcohol stoves like air drafting in from the bottom. After visiting QiWiz's site I'm not sure those elongated holes provide enough combustion air.
Try raising the windscreen off of the ground / surface 1/2" to 3/4". For the purposes of experimentation you can use some large paper clips on the windscreen as legs.
Judging from the pictures I would suggest a 5" diameter pot minimum and maybe as large as a 6" to avoid the obvious flames running up the sides.
NewtonMar 9, 2013 at 5:51 pm #1963636
Yes, efficiency is my goal. I don't care if I need to wait for water to boil. I'll tinker with the windscreen a few times and see what I come up with.
Still would love to know the best way to pour from the stock container without spilling…even when pouring into a smaller bottle.Mar 9, 2013 at 6:01 pm #1963640
@annapurnaMar 9, 2013 at 6:15 pm #1963652
Thanks Anna! I'll see if I can find the same thing locally.Mar 9, 2013 at 6:28 pm #1963662
the little measuring cups for kids medicine work good when playing around at home.
just make some mark inside the stove , a fill line, and fill to that when you are in the field. It can be as simple a sticking on a tiny piece of aluminum tape. Or scribing a line.
No need to bring the measure with you. One more thing to keep track of.Mar 9, 2013 at 6:30 pm #1963663
Yes, you can easily find these things cheap and locally,I figured it is easier to know what you are looking for with a visual.I can get all the free little measuring cups I want for free,my mom is in a retirement home and it is what they bring her pills to her in.Mar 9, 2013 at 6:37 pm #1963665
Yeah, the visual is great. I was thinking that was what I needed.Mar 9, 2013 at 7:04 pm #1963675
I didn't find any paperclips on hand, but found 4 black clips that raised the windscreen up about 7/8".
I used about the same amount of fuel. At first, the flames were much smaller and seemed to barely even come around the side of the pot. I was thinking I had this thing figured out.
And then about half way into the boil, the flames started spilling up the sides. This time, it was only in two concentrated spots, not a large area.
I forgot to start my watch, but it was definitely faster than the first boil. What can I learn from this?Mar 9, 2013 at 8:38 pm #1963710
@bruckyLocale: Central Cal
To me it looks like the stove is getting too hot. When the stove gets too hot it forces more alcohol out the jets and it burns faster and higher. It happens for a couple reasons I know of…1)stove design, the jets are too low and the flames lick up the side of the stove and heat it too much 2) Too much heat is trapped by the windscreen or 3)you put in too much alcohol causing higher pressure. 1 oz of alcohol should be enough.
Those beer can/bottle stoves have a good size diameter so they usually do better with a larger pot. Tinny at minibulldesigns recommends 4 inches or larger for his stoves.Mar 9, 2013 at 10:59 pm #1963782
@newtonLocale: Southeastern Louisiana
"What can I learn from this?"
Does your stove and your cook pot form a "seal" where they meet? If they do you could be over pressurizing the stove's jets as everything heats up.
Can you increase the circumference of your windscreen so that the gap between the cook pot and the windscreen is larger?
Some of the bottle stoves use raised dimples where the cook pot rests on top of the stove. Does your stove have these raised dimples? If not try a burn with a "triangle" of SS wire between your cook pot and your stove. .020" or .030" SS wire should be a large enough diameter for a trial run. This may help in reducing some of the pressure at the jets.
If it does then you have to decide if you want to "dimple" the top of your stove. ;-?
In the picture below there is an example of what I am describing.
Look closely at the top left of the stove in the picture for an example of the dimpled top on a bottle stove. There are three dimples spaced equally around the top where the cook pot rests.
The stove in the picture is made from a 6 oz bottle but the principle can be applied to a 12 oz bottle stove.
I would think that you could accomplish the same thing by using a round file and "cutting" 3 reverse dimples into the stove's top rim being careful not to cut them completely through the coped rim. ;-?
This modification would be irreversible!
Make each test burn changing only one thing at a time.
NewtonMar 10, 2013 at 6:01 am #1963806
I'll see if I can use a paperclip or something to keep the pressure from building. I was wondering if that was the issue. Only one way to tell. R&D tonight!
One thing I noticed is there is soot on the windscreen, but not on the pot or the stove. It's predominantly on the side where the flames were tall and orange. I'll take that to mean the fuel wasn't burning as clean as it should have.
And no dimples on my version. I might add those later depending on what I find tonight.Mar 10, 2013 at 4:14 pm #1963993
@jonfongLocale: FLAT CAT GEAR
1)I suspect that you are getting yellow flames is that the ethanol content may be too high. Look up the MSDS online to check the percentages. On solution is to add a little water to your fuel to calm it down a bit.
2)Fuel measurements. 1 tablespoon = ½ ounce of fuel. 1 teaspoon -1/6 ounce of fuel. A typical bottle stove like that will use ¾ ounce to boil 2 cups of water.
3)For grins, you can take a picture of the stove burning with the windscreen (showing the yellow tips and then remove the windscreen and look at the flames. If you see a big difference, then there is probably a windscreen/stove/mug interactionMar 10, 2013 at 4:25 pm #1964001
@b-g-2-2Locale: Silicon Valley
What is the metal surface with the diamond pattern? That might be such a reflective surface that it is changing the stove performance. Normally the burner is sitting on the ground which is not so reflective.
–B.G.–Mar 10, 2013 at 6:45 pm #1964041
@danepackerLocale: Mojave Desert
I think that for THE best efficiency you should get a Caldera Cone stove.
I have not found anything close to a Caldera Cone for fuel-to-heat ratio with alcohol, ESBIT or wood.
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