SUL Windscreen for BRS-3000T Canister Stove

[David Gardner]

I love the BRS-3000T canister stove for its light weight and low cost, but like all “bare” canister stoves it is much less efficient in the wind. It’s not safe to use a windscreen that encloses the canister, so I wanted to design a simple windscreen that enclosed only the burner. The concept is an inverted cone that rests on the base of the BRS-3000T, just below the mixer holes in the stove pedestal. I used the Zen Stoves conical windscreen design tool (http://zenstoves.net/PotStands-Conical.htm#ConeTemplates) The lower part of the stove pedestal is 0.5" in diameter, so I used that as the “top” of the cone. I put a beer can pot on the stove and measured the clearance, and came up with 4" for the “base” of the cone. I added 0.25" for flat lock seams at the ends. I drew and cut a paper template to check the fit, then traced and cut the shape from some .004" stainless shim stock. Paper template .004" stainless steel shim stock I didn’t want to use titanium foil if it wasn’t going to work, so I made it from stainless steel first for testing purposes. I punched a row of 5/16" holes around the opening for the stove pedestal, but initial tests showed that not enough combustion air could get in, so I punched in a second row. The finished product Did test burns in the shop first just to verify that the windscreen did not detract from performance, five burns without the screen and then five burns with the screen. Average time to boil 500.0 ml without windscreen was 7:03 min using 6.0 grams of fuel. Average time with windscreen was 6:47 min using 5.8 grams of fuel. So it actually improved efficiency about 3%. Then I set up a box fan outside and turned it all the way up, which produced a steady 4.4 mph breeze, and again did five burns without the windscreen and five burns with. Average time without windscreen was 10:31 min. using 9.0 grams of fuel, versus 8:50 min and 7.5 grams with the windscreen. An improvement of about 16%. Measuring wind speed The windscreen weighs 9.4 grams in stainless steel. Titanium should be about 6.3 grams. The windscreen fits easily inside my cook kit. This brings the total weight of my kitchen (700 ml pot, pot lid, lip guard, 1 qt. bowl, 16 oz. cup, cozy, stove & mini-Bic) to 5.4 oz and the cost to about $30.

[Gary Dunckel]

That looks pretty sweet, David. Very clever idea. I've found that the BRS is in fact a bit more finicky in a breeze than many canister stoves. It looks like you've found a great solution for this.

[Jon Fong / Flat Cat Gear]

David, Nice design! Did you define the outlets gap by the width of the arms?

[David Gardner]

Thanks Gary. Jon, I defined the top of the cone as 3/8" clearance around the base of the can pot. Working on an improved screen with a cylindrical top portion that rests on the cone. Early results are very promising.

[HeathP]

That is really cool! Anyway you could make a shorter one so you could set a wide pot on the BRS-3000T? I'd buy one!

[David Thomas]

DavidG: Very nice! 4.4 mph isn't much of a breeze, and even in that mild wind, you're saving enough fuel to justify the weight of the wind screen in 6 boils (if using SS) and only 4 boils (with Ti). I look how close you've now got the hot gas flow past the bottom perimeter of the pot and think, "some HX fins there would do a lot to decrease boil times and fuel consumption". I look at the last photo and it all seems compact until I realize that is a mini-Bic, not a standard. Very compact!

[David Gardner]

Heath: I will try making a shorter windscreen that will work with larger pots and report the results. David Thomas: 4.4 mph seems like a small number, but the breeze felt very substantial. I'm not sure I've ever actually tried to cook in that much wind without going inside a tent. What are "HX fins"?

[Jon Fong / Flat Cat Gear]

David, Stove performance in the wind is actually an interesting topic. It really depends on where your cooking system is located (preferably at ground level). Classic fluid dynamic will say that the steady state velocity at the ground is zero. I have done several field measurements looking at the air velocity from about chest height down to the ground. Depending on the substrate, I have seen a 3X to 10X reduction in wind velocity at ground level. So it depends where you place your stove and where you are measuring the wind. 4.4 mph at chest height will not have a great effect at ground level. This is why it doesn't make sense to raise your stove up on a bench or table to cook.

[HeathP]

David, I am using a Toaks 550 and an Evernew 1.3 liter. Would love to buy one that'll fit both if you get it worked out. Thank you!

[David Gardner]

Heath, I just did some tests with a short windscreen and a wide pot, and it performed very poorly. Apparently one of the keys to success of the original design is that the cone extends outside and above the bottom of the cook pot. Also by coincidence the size of my cone is just right for the pot supports of the BRS-3000T to hold the cone in the correct position. I could go a little bigger…what is the diameter of the Toaks 550?

[HeathP]

Sorry for the delay it appears to be 3 7/8 at the top lip roughly.

[KRS]

I have the Olicamp ION Micro titanium stove, it is just the more expensive version of the BRS-3000 stove. I have noticed my stove has a horrible time if there is even the slightest breeze. I have been trying to think of a ways to make a wind screen for mine and I think you have done all the work for me. Thanks

[David Gardner]

Hey Kurt, give it a go and share your results! Here is a picture of a the basic cone supplemented with a cylindrical upper that I recently made. I will run some boil tests when I get a chance and report. If there's enough interest, I might whip up a batch of windscreens to sell.

[Bob Moulder]

David, that looks great but I'm wondering if the burner will be starved for O2. Looking forward to your burn tests with the supplemental screen. Should improve fuel economy a lot… typically I'd expect 4.5-5g to boil 500ml.

[Jon Fong / Flat Cat Gear]

If the windscreen is tall enough, you might be able to raise the mount points (thereby lowering the bottom edge of the windscreen) and not need the cone on the bottom. Just a thought.

[David Gardner]

David: With the supplemental windscreen I got 4.9 grams to boil 500 ml of water. Big improvement. Unfortunately, in the wind the flames simply blow out. Big "dis-improvement." Jon: Interesting idea. I'll have to give it a try. Especially since the cone combined with the cylinder doesn't work in the wind.

[Ben H.]

It is really interesting that (if I am reading you correctly) the supplemental section, far removed from the burner, caused the system to be susceptible to wind. I wonder why that could be. Did you try out any full windscreens (that don't completely surround the pot)? Or did you want to stay away from those designs because you plan to sell them? Also, to answer your question from Dave… HX is an abbreviation for Heat eXchanger. He was suggesting adding fins to your pot.

[Bob Moulder]

the supplemental section, far removed from the burner, caused the system to be susceptible to wind. I wonder why that could be. Wind eddies? I don't know the formula/design for doing so, but notice that the windscreen on what is perhaps the most wind-resistant stove on the planet — that of the MSR Windburner — has a lot of holes in it that reintroduce some turbulence to "backfill" the high negative pressure of wind eddies. Probably needs some holes around the bottom perimeter.

[Ben H.]

I suspect you're right. Flow around the windscreen produces low pressure spots downstream. Vortex shedding makes the pressure cyclical. The periods of low pressure suck air out of the burner. The initial design sucked air in at the top to replenish what was leaving. Adding the extended screen gave flow too long of a path to reach the burner. During the period of low pressure the stove gets snuffed out. Punching a few holes up high on the cone may fix the issue.

[Jordo _99]

David, you asked someone else the diameter of a Toaks 550ml…it's 3 3/4" (I've got a 650ml and it's the same diameter, only taller…I believe the 750ml is too). I'd be interested in a Ti windscreen if you decide to sell them too.

[David Gardner]

Ben & Bob: I punched a ring of holes around the bottom of the supplemental cylinder and it did not help at all. Then I punched a ring of holes around the top of the cone, and if helped a great deal! Unfortunately I used up my last canister on the first test burn so I don't have results to report yet. I'll pick up some more canisters today. Jordo: I should be receiving a Toaks 550 to test soon. I've already made a slightly larger windscreen for it. I'll do some tests when it gets here and report the results.

[john karnes]

David, I use a BPL550 and am ready to buy this set-up when it is available for sale if you chose to make up a batch. John

[David Gardner]

Cool John. I'll post if I make a batch.

[Edward Barton]

David, I’m curious, did you make any more headway with this project?

[Brad Rogers]

curious as well………..

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