Similar stove to Super Cat that'll work more effecient with BOT pot?

[Rusty Beaver]

I’ve been using a Super Cat stove for 10 yrs, combined with a fairly wide ti Snow Peak pot. I love the stove for its weight, simplicity, etc…and have been more than happy with its efficiency. Also, my fuel bottle (PB8 probiotics bottle) fits into the stove like it was made to.

I recently switched from my Snow Peak pot to the narrower BOT…and, though I have not done any timing, I have noticed a loss of efficiency. Many of the flames simply go up the side of the BOT.

Is there a similarly simple stove I can make that will work better with my BOT? Perhaps another variation of the Super Cat? Or, is there a way to make this set-up more efficient? (I did not have a dedicated windscreen on this last trip so perhaps that is where I should start. Maybe all I need?)

 

[Ben H.]

Well, wide pots do a better job of absorbing heat that tall narrow pots, so a simple stove replacement won’t cure all of your troubles.  That said, I’m guessing a startlyte type stove would work better than a super cat.  Continuing, yes, a wind screen should really help you out upping your efficiency.

[Gary Dunckel]

Zelph’s Fancee Feest stove might work a bit better. The wick inside the cat food can will bring the flames closer to the center of the pot, and the integrated pot stand will guide the flames upward. While it’s true that a wider pot (like an MSR Titan Kettle) would be more efficient, I have had decent luck with a similar stove that I came up with myself, and it works OK with my BOT 700 pot. Here’s what it looks like:

Zelph and I both came up with the same stove design nearly 10 years ago. He uses a wick of fiberglass and a pot stand made of titanium foil. My wick is simply a strip of carbon felt, with a ti foil strip for the pot stand.

The use of a wind screen is critical, in my opinion, for both alcohol and Esbit stoves. It also helps when using a canister stove in breezy conditions. Here’s my alcohol/BOT setup, using a MYOG cone that just happens to work with several pots that I use:

In the background of the first photo, you will see several iterations of the same stove, where I replaced the titanium foil pot stand with various cans that have the perfect diameter to fit inside the carbon felt strip–a tomato paste can (steel, .92 oz.), a Dole’s pineapple juice can (slightly lighter steel), and an aluminum Perrier drink can. The steel cans are the most bomb proof, and the Dole’s is .82 oz. The Perrier can is the most fragile but it’s the lightest (.51 oz.). My ti version is pretty light as well at .53 oz., and it’s well able to support 2-3 cups of water weight without deforming.

OK, so that was too much information. The point here is that you need to have a more narrow flame pattern so that the flames don’t go up the sides of the pot, and also that the use of a wind screen is important.

The BOT 700 is an interesting pot, isn’t it?

[Rusty Beaver]

Thanks, Ben and Gary!

Gary,

Yes, the lil’ BOT 700 is pretty neat, I think. And that’s the reason I’d really like to have a stove that worked well with it. Wish there was a way to continue using my Super Cat or another similar stove, so that I could also continue using my PB8 probiotics fuel bottle. Perhaps I could find another bottle that would work with a Fancy Feast. Or, maybe the windscreen with my Super Cat will give me what I’m after. Any way, no worries with giving me too much info. I appreciate all the info I can get!

By the way. Can you tell me about the tubing on your BOT handles?

[Gary Dunckel]

Rusty, the handle tubing is silicone. It works great to insulate your hands from hot pot handles. I’d like to help you tweak your setup, and I have a couple of ideas. Why don’t you shoot me an e-mail , so we don’t clog up this thread. Send it to:  drzooz (at) aol (dot) com.

[Rusty Beaver]

I’ve been testing my current Super Cat with and without windscreens and the results are leaving me scratching my head.

My stove specs: 3 oz cat food can with 15 3/16″ holes on the top and 10 3/16″ holes below. I used the Super Cat Zen stove template.

I’m using the new BOT 700 pot with lid on….with 2 cups tap water measured at 70°. My tests have been done inside my shop on the work bench. Each test has been with ~3/4 oz of Everclear 190 fuel.

My first test, to full boil, with no windscreen = 4:30. Much better than I thought it would be!

My next tests were with alum windscreens, vented slightly at the bottom, ranging from tight around the pot to within 1/8″ away. Couldn’t get a boil with either. Not surprisingly, the tight one choked the fire out.

For the next test, I made a screen out of tinfoil which was 5/8″-3/4″ from the pot and and 10 3/16″ diameter holes near the bottom, evenly spaced. The flames shot up the side of the BOT and past the top by 6″! I ran out of fuel at 5:10 and did not get a boil (water was just starting to bubble). Also, I was getting a 6+ minute burn time before, with no wind screen.

Two surprises with these tests: 1) a boil time of 4:30 with the narrow BOT and no screen AND 2) a faster burn and no boil with a screen. I’m confused!

Can any of you stove techs explain what’s happening and what I might try next? I’d simply continue testing but I prefer the 190 proof which is difficult for me to get, expensive, and I don’t have much left.

 

[Jon Fong / Flat Cat Gear]

This is happens more than you think

1. No windscreen Time to Boil 4:30 burn out at +6 minutes.  A lot of heat is going into the pot as well as up the sides of the pot
2. With the windscreen (5/8″ to 3/4″ annual gap), no boil, flames shooting up the sides, Burn out in 5:10.    The Super Cat is a hot burning stove.  To boil water in case 1), the stove is putting out +400 watts.  With small diameter cooking systems, the burn volume (volume defined by the windscreen diameter and the ground to pot height) is small.  Think about the temperature rise when you put a 100 watt light bulb inside a 1 cubic foot box.  If the box volume is reduced to 1/4 cubic foot box, the box will get hotter.  The Super Cat stove is overheating and the vaporization rate is increasing (hence the fast burn out rate).  The vaporization rate is high enough that the stove can be starved for air and self extinguish.  The unburnt alcohol vapor rises up between the pot and the windscreen where there is fresh oxygen and burns (the 6″ of flame over the top).

I suspect that if you increased the gap to 1″ to 1 1/2″ that the flames will no longer shoot out over the top.  I also suspect that your stove will still be burning hot and that you will not get the 4:30 time to boil  because the flame spread will be too big.  My 2 cents, but I may be wrong.  the best thing to do is to test it out.

[Bob Moulder]

Needs more air inlet at the bottom.

[Zak S]

Agree, more air at the bottom. You’re getting taller flames because the stove is producing as much or more alcohol vapor, but it’s taking longer for complete combustion because there’s not enough oxygen.

[Matthew / BPL]

More air at the bottom would be easy to test with a hole punch. Please share the results of further testing.

[Rusty Beaver]

Thanks to everyone for their input.

For sheer ease, I decided go with the line of thought of extra airflow at the bottom. Rather than poke holes in it, I simply elevated it up with 1/4″ bolts I had laying at hand. Laid them flat and placed the windscreen on top.

The flames did not extend up as high as before….and I got the water to boil at 5:15. The stove burned out at 6 mins.

I probably would have gotten a slightly faster boil time but with the screen now ventilated this much, I was curious how effective it would block the wind. I blew towards the screen at a number of different angles, to stimulate a breeze. Just a slight blow whipped the flames around.

That said, I’m now scratching my head again…wondering why I’d haul around a wind screen that slows my boil time, cuts down total burn time, and may offer little if any advantage in a breeze.

I wish 190 wasn’t so darned pricey….and tough for me to get. I could burn through quite a bit of fuel testing varying configurations.

That said, I’m going to try Jon Fong’s idea next.

Also of note, when I used to sleep on a foam pad, I used it at least once as a wind screen with my Snow Peak Giga Power….rolled around the stove. I just held it in place so the wind didn’t blow it into the hot stove. I thought I had the world’s best windscreen! I tested my Neoair in the same way…but it doesn’t work stand as well as the foam….and if it came in contact with the flame, I’d be without any cushion the rest of the trip!

[DAN-Y]

Make new supercat with one row of holes close to top of can. Reduces burn rate and increases fuel efficiency. Also inceases boil time. Reduces flame spread.

Cut inverted V notches at base of windscreen instead of poking holes. Use denatured for testing, use 190 when hiking.

[Rusty Beaver]

Thanks, Dan Y. Great idea to test with the cheaper denatured stuff. When I get the time and ambition, I will make a new stove as you suggest.

I ran some more tests with what I had. I tried Jon’s idea of spacing out the distance between BOT and screen to 1″+. Unfortunately, no luck. Burned out at 6:25. No boil.

I did have some luck with another method though. I used the same foil screen, covering up the holes at the bottom and cutting a single large one opposite of the handle. I then folded the top over so there was 1/8″-1/4″ space between screen and BOT. Quite a few flames went up the BOT. However, the  sides started boiling at 4:30….and I had a full rolling boil at 5:30. Total burn time was 7:20. 1 oz 190 (I remeasured & my stove does in fact hold 1oz instead of the .75 I recently estimated)

See the pics below. Quite a mess of a screen but it gives me something to work off of. Was hoping to have a simpler design…but that’s what I have for now. I didn’t want to mess with a cone but perhaps that’s where I should head next…using the same top and bottom diameters as this thing, with a single large hole opposite the handle.

(all input/ideas/wisdom/thoughts welcomed and appreciated)

 

[Rusty Beaver]

Well, I made a cone screen (alum flashing) with the same sized single bottom vent and same (roughly) bottom and top diameters as the above foil mess of a screen. I started with an average of ~1/4″ gap between screen and pot on the first test and got a boil at 5:55. I closed the gap to an average of ~1/8″ and got a boil at 5:35 with total burn time of 7:10.

It was at least 15° cooler tonight compared to the tests mentioned in my previous post….so that may have slowed things down, I don’t know.

Fun stuff. I could see myself puttering with different styles and designs all winter! Definitely want to try the Super Cat Dan Y mentioned with one row of holes.

I welcome any comments, thoughts, or input anyone would like to share. (ie, bigger vent at bottom, tighter fit up top, etc, etc)

 

 

 

[Rusty Beaver]

I just noticed something: A little soot on my pot, around the handle area. Not sure if I got it from the first test with the cone or second. Never noticed soot before, on this BOT or other pan used with this stove and fuel.

Any idea why? Incomplete combustion? Something else?

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