Canster stove windshield development

[Stormin]

[Stormin]

[Stormin]

Part two: https://youtu.be/NTLlcOKpUus

[Stormin]

Part two:

[Stormin]

Stormin canister stove windshield development continues, part 3.

[obx hiker]

This windscreen looks interesting . A few questions if you have the time.

1.Brand name of pot? Pot diameter? I like that removable handle and Toaks makes a 750 ml pot with a 3.75″ diameter and NO handle.

2. Brand name of stove?

3. Any reason you couldn’t take one of your cozy’s, cut off bottom to fit below silicon ring and leave top of the cozy on the pot while cooking? In effect a 2- part cozy, or 3 with a lid, which BTW also could serve to shield the pot and packed contents somewhat from damage while in the pack Once you remove the pot from the stove slip on the cozy bottom, then drop a little reflectix lid in place and as you put it “go about your duties”  whilst the meal simmers. I’ve been leaving a reflectix cozy on a jetboil 650 ml pot for years, but of course couldn’t insulate the bottom. This might work even better unless somehow the heat exchanger fins on the jetboil pot are continuing to heat the pot more so than the heat lost due to lack of insulation

 

Oh and of course how much does the screen and added silicon ring weigh?

 

Thanks!

[Stormin]

<span style=”font-family: ‘Helvetica Neue’, Helvetica, Arial, sans-serif; font-size: 13.5px; line-height: 23.4899997711182px; text-align: center;”>@obxcola, The pot is my own design Storminstovesystems.co.UK</span>

750 ml and 95 mm diameter.gr2 titanium with a wall thickness of 4mm.

The stove is unbranded, I will also add my brand name to it.

The cosy already serves to protect the pot while carried in an outer mesh pack pocket. I can’t envisage making a three part cosy, too much faff. Also no fins or hx on my pots.

Windshield weighs 24g, silicone band 6g.

 

[obx hiker]

I didn’t see the pot or windshield on your site. Look forward to seeing those items listed. The screen shield appears to be very well designed.

Thanks for the reply.

Like that term “faff”  I guess that substitutes for “Fiddle Factor” or maybe it’s an abbreviation? Must be Anglian English?   ;)  I guess my tolerance for “faff” is a little higher since I can’t see a removable  cozy bottom while the top is basically continuously in place would be that much trouble to slip on after removing the pot from the stove. And the “cozy” lid; well that’s practically weightless and can also stay on the pot most of the time, especially when the whole kit is bagged up

I guess I was just wondering if you thought a truncated cozy applied just above the band would be damaged while heating water with the screen and band in place. Since you’ve possibly not tried this I suppose it’s conjectural. I’ve done it for years with a jetboil; with the cozy all the way to the bottom  (but not over the bottom!) of the pot and it’s been no problem and actually a convenience but that’s a different setup.

There’s lots of ways to conserve heat, and therefore conserve fuel. That said I’m no engineer.

What I’m trying to determine personally is a system that would lighten up my existing jetboil system        (8.1 oz/ 233 gm.) without adding a fuel penalty. I’ve been getting about 6 days or 16 low boils from 100g canister heating @450 ml. It’s fast and easy. No faff! But I’m wondering if I couldn’t due the same or better with a better stove and lighter pot with no HX, so the screen looks good. I can save @ an ounce with a different stove with no built in base (Jetboil is 104 gm), and another 2 to 2.5 with a pot that isn’t hx.  (jetboil 129)  Add back @ 1 oz for the screen and band.and that’s @ 2.5 oz less. Will the new rig work as well is the question F and F. Fiddle and Fuel  ?

Add ounces here, take away there…..

 

 

[Stormin]

obx hiker, first a correction to my previous post. The pot wall is .04mm thick, not 4mm. Faff means messing around with something not relevant to the immediate task/job in hand. Your figures are confusing in relation to your Jetboil system. I cant find any Jetboil system under 350g.

A truncated cosy would not work if placed over the lid/pot rim. The diameter of the cosy would be too large to be supported by the silicone band. Also the handle fixing and handle would prevent this, unless a piece of the cosy was cut out to allow this to work. Like I said, too much faff. The total weight of my system, pot+lid+stove+cosy+silicone band =240g.

 

[Mark Fowler]

I think you mean 0.4mm which seems the standard although Evernew do 0.3mm.

A major savings on most pots is to get rid of the handle and replace with a thin flexible wire bale handle.  You have done a great job in the building of the windshield but do you get any slippage when the system gets hot? Personally I prefer to keep things as simple as possible and don’t try to nest everything into the pot. I feel it adds a number of limitations such as having to remove the windshield to fit the pot in your cozy.  For comparison my 900ml setup with pot, lid, windshield, stove, cozy, stuff sack and lighter is 160g. The big savings are in the bale handle. The bale handle also removes the need for slits in the side of the cozy to allow for the rigid handle.

[obx hiker]

Stormin the stove I have is a discontinued model linked below. I got rid of the neoprene cozy, the lid and the canister stand and added back a reflectix cozy and reflectix lid. It weighs 8.1 oz or 233 grams; pot, cozy and stove.

jetboil flash lite

The lip of the pot or the handle attachment can be an issue with the cozy. That’s one thing nice about your handle. At least it doesn’t have TWO bulky handles to try and work around. The lip problem is simply solved bu sliding the cozy up from the bottom, and yes I made it tight. With a handle like yours I’d have to make some sort of notch maybe like a “u” shape so the handle sides could fit in the vertical cuts and the flap would be pulled back through the handle and possible re-taped. BUT that wouldn’t work with the rivet spacers inside the windscreen hence the idea of a permanent top part above the windscreen cozy and a second bottom part you’d remove when the pot’s on the stove/inside the windscreen. The one you’ve made looks like it would work perfectly well, just cut off the bottom part up to the windscreen level and leave the top on all the time.

Mark Fowler do you remove your cozy when you’re heating water or does it cover the bottom of your pot?

What kind of stove do you have?   I like that weight savings with a wire handle.

What do you use for a windscreen?

[Mark Fowler]

obx – I remove the cozy when the pot is on the stove as the cozy relies on the stuff sack for some structural support and protection. Using 2 layers of 3mm foam glued together delivers slightly better insulation performance compared to reflectix and only weighs half – 14g vs 29g – 6g for the sil-nylon stuff sack. The foam lives in the stuff sack and is never removed, the stuff sac is just folded down when needed.

The stove is a BR-3000T in a little stuff sack which also holds the mini bic lighter. I always keep my stoves in a separate stuff sack to help prevent dirt getting into them. The windscreen is just Al flashing cut to size (29 grams).  I fold it into quarters and slip it into a side pocket of the pack.

For a flexible wire bale handle to work the pot needs to be quite squat or long and narrow; shallow, wide base pots become too tippy.  The pot am using is an Evernew ECA265 without the frypan lid (105mm high by 118mm diameter) Removing the old handles saved 19 grams while the bale handle adds back 1 gram. The lid is reflectix (3 grams)

[obx hiker]

Thanks Mark. Picture/1000 words…… looks like a really nice system. I take it you’re just trying to use the screen to keep wind from messing with the stove flame and not as a sort of variation on or substitute for an HX pot like a jetboil pot. This leads to 3 questions.

Is an HX pot worth the extra weight?

Does a tight fitting windscreen serve as an effective substitute for an HX pot? 4.5 oz for the 800ml jetboil

Is either one really necessary instead of a simple free standing wind blocking windscreen?

[Mark Fowler]

obx – The wind screen is exactly that, not trying to get it to do double duty although I do use it as a cutting board on occasions. It will of course reflect a bit of heat onto the pot as does the fitted wind screen, as well as adding a bit of turbulence to help heat transfer.  I expect a couple of studs making contact with the pot will transfer very little heat to the pot but I am happy to be proved wrong if some does the experiments. There have been a few concertina type windscreens trialed by Jerry Adams, I think, that had a lot more area in contact with the pot.

My take on HX pots after a bit of experimentation and reading many posts is that for 3 season use – no, the added weight is greater than the fuel savings. They come into their own in situations where you are using a lot of fuel per day – snow melting, big group etc.

My preference is usually for the simplest, most flexible solution rather than one that is engineered for far more specific circumstances.For instance my pot works well on a stove but also on an open fire, bale handles are easier to lift on and off a campfire. On a campfire, wire side handles can become very hot requiring gloves/pot lifter, hx fins may melt and neoprene/reflectix wraps are also likely casualties.

[Roger Caffin]

My preference is usually for the simplest, most flexible solution rather than one that is engineered for far more specific

I like.

cheers

[JCH]

simplest, most flexible solution

Yep.  Every time.  I like Mark’s setup.  Well sorting it seems.

[James Marco]

Yes, quite…

Any analysis of Heat Exchangers will show that they only approximate a wider surface area at the bottom of the pot. Increasing the overall surface area of a pot bottom will have the same effect. To demonstrate this I made a series of pots (all starting with a Stanco or KMart grease pot at 3.5oz holding a quart of water.) The last had 9 concentric rings pressed into the bottom after annealing the bottom. This shows an approximate 13-15% increase in the bottom surface area with a commensurate fuel consumption of about 10-15% less fuel used. As such, I deduced that the the action of a heat exchanger is to simply gather excess heat and transfer it to the pot.

Anyway, the overall fuel consumption dropped about 15% due to the otherwise wasted heat (usually up the sides. The laminar gas flow, as it rolls around the corner of the pot, actually speeds up a bit, so it makes sense to have the heat exchanger extend about 1/3-2/3 of the way up the pot.  As such, any turbulence in the air stream, reducing heated air velocity, and, holding it near the pot works well. The rivets work well for this regardless of not being connected to the pot. They slow the escape of hot gasses along the sides. The wind screen/heat shield actually hold the hot gas next to the pot, and, the interruptions to laminar flow (the rivets) slows the escape of the hot gasses further, allowing the better heat to transfer along the sides. Coupling a standard HX pot with either rivets (or bent fins) along the side of the windscreen heats water very well.

Since there is an overall decrease of about 15% in fuel, there is about a 6day consumption and one free day from the savings. Using both HX pots and a windscreen can result in about 4 days normal use with a 5th day free. However, the weight of the extra rivets, sort of cancels out the increased fuel savings. The same goes for fins. Unless you are on a long 10-15 day trip, you don’t realize enough savings to paw for the extra weight…Pay in lost fuel or pay in extra weight to save fuel… The same follows HX pots generally. Any additional material adds weight.

Dimpling the bottom of a pot does NOT cause extra materials to be added. Starting with a 3.5oz pot, means you end up with a 3.5oz pot, but, reduce fuel consumption by around 15%. I don’t understand why this doesn’t make as much sense as a 5oz HX pot that saves and extra 15% over the long haul. The turbulence inducing wind screen can be used in either case, so is discounted.

The only down-side is that the rings show up inside also, making the pot a little more difficult to clean. No biggie, really. A wash with your fingers and a couple ounces of water, then wiping it all out with your bandanna gets it clean enough.  Food requires water to spoil, so dried on bits don’t spoil nor make you sick, regardless of how dirty the bandanna is. You will boil the pot again in 12 hours, “sterilizing” it again.

[Jerry Adams]

That makes sense, more effective surface area

another thing is to direct more of the exhaust to next to the pot where the heat can be absorbed

like the first picture in this thread

or a caldera cone

or just about any windscreen will reduce the amount wind blows the exhaust away from the pot

[James Marco]

Jerry, yeah, assuming a pretty stable interior flame (usually on low, it saves about 20% over medium, and nearly 100% over high) the gasses rise to the pot and spill over the edge, much like water does over an inverted pan. Depending on the hot air flows, it will often just curl once around the pot and establish a laminar flow thereafter. Breaking this up will produce a LOT of curls as hotter gasses come into contact with the pot sides, again, assuming it is maintaining heat as it rises. Some is lost through the windscreen, but the rest is directed back to the pot as it curls up around any obstruction. Theoretically, a helical screw will provide the most transfer, but weight becomes a bug, again, let alone the trying to form the pot into the screw shape. You would need a highly insulated windscreen and low heat to reduce the flow to a maximum. I usually test the flow by putting my hand over the pot. If I feel a blast of heat, I am running too high.

A caldera cone is good, but it sheds heat. It is more designed to supply a windscreen and pot support. A straight tube with some sort of break-up of the laminar flow would provide better heating lower down. As the heat rises, it will loose temp to the pot and becomes less important for heating the water. Indeed, in my Grease pot, (usually half full) a lot of heat is lost because the water is not in contact with the sides. Heating the pot/water would be more beneficial if the hot gasses were broken up more. An insulated, straight  wind screen would be another 5-15% more efficient. This assumes that the screen is not tight with the pot, but allows cooled gasses (at lower lift/velocity) to escape easily, maintaining a good airflow to the flame.

Yeah, ASSUMED stable combustion environment is the watch word. Without any windscreen this is all lost except at the venturi area immediately behind the pot. Conclusion? Always use a wind screen.

 

[Stormin]

This thread is about my canister stove windshield, seems to have been hijacked by hx pot x windshield x insulated pots, redundant jetboils and the like. There is already a thread on that subject elsewhere, take your traffic there.

[Roger Caffin]

The last had 9 concentric rings pressed into the bottom after annealing the bottom.

PHOTOS! Please?

Cheers

[James Marco]

OK, here is the one I most commonly use, it has 7 concentric rings. The other was given away, sorry.

Uhh upload error, I’ll try to shrink it a bit.

You can see that the pot has been heavily used over the past 10-15 years. It’s just badly dinged up these days, but still going strong!

 

 

[Roger Caffin]

Ah, I see. Thank you. I have never tried that sort of idea.

Question: do you have any comparative performance data? Same stove at same power heating same amount of water over same temperature range: time to boil and fuel used.

Cheers

[James Marco]

Yes and no. I had done a few hundred test runs with a plain pot, a dished bottom pot, 3-ring pots and 9-ring pot about 10-15 years ago. Subsequent computer deaths (3 or 4 iterations) finally did that data in, so, no I don’t have it anymore. It can be duplicated but I just don’t want to spend 3 weeks of watching alcohol burn all day. (Semi-retired for a couple years before I actually retired permanently.)

 

[Roger Caffin]

No backups? Ah well, no matter.

Cheers

[Author]

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