The Evolution of a Winter Stove – Part 3

[Ken Thompson]

Roger volunteers all him time and effort here at BPL. Throwing money at BPL unfortunately will have no impact on Roger. If BPL was to cease Roger would have more free time to get stoves done. Catch 22.

Nice stove Roger.

Thanks for everything!

[James Marco]

Well, to be fair to Roger, BPL and all readers, specs are simply not available.
It sortof depends on how you plan on using the stove, ie, wind/heat screen, pot size, snow melting or not, boil and dump cooking vs real cooking, temp of water, temp of air, and a lot of other factors that are debated in several hundred threads on stoves here. That said, I am looking at getting about 14L boiled out of a single 100g canister. This is slightly less efficient than what I get out of my SVEA. (I get about 14L out of 4.2floz of WG or adjusting for density to weight about 14L/3.276oz or 14L/91.728g.) But the weight of the outfit is finally significantly less. Every other set-up results in carrying MORE weight over my average trip length of about a week.
Roger's stove:
3.3oz/90g (actually it might weigh a bit less, but I have not received it yet to weigh it.)
100g Jet Boil canister + 100g can (200g total or 7.143oz total)
Pot: 3.25oz/91g
Cup: 1.625oz/45.5g
Wind/Heat screen: 1.75oz/48g
TOTAL: 17.068oz/477.904g for about 5 days at my usage (2 liters per day plus simmering.)

SVEA: 17oz
Cup: 2.625oz (cover for transporting stove)
4oz of fuel + bottle: 5oz total or 140g (for 6 days out at my usage)
Pot: 3.25oz/91g
Wind/Heat screen: 1.75oz/48g
Total: 29.625oz/ or 829.5g for 5 days at my usage(actual tested usage.)

Both are UL setups, and NOT a typical SUL setup. I do a lot of real cooking. Soups, stews, rice, etc. So, for a week out,I would carry about 24oz with Rogers stove. I would add another 4oz in fuel for the SVEA at about 34oz. I WILL go for that at about a 10oz savings.

I would strongly suggest buying a membership.

[Jerry Adams]

Roger's stove has the canister remote so you can turn the canister upside down so you can use it in colder temperatures. Regular canister stove is good down to maybe 25 F. Inverted should be good down to boiling point which is maybe 12 F. Also, the burner is lower in the air so less susceptible to wind.

Roger's articles are worth the price. He addresses a number of problems and goes into infinite detail.

14 L boiled out of 100 g canister?

I use 1 oz per day. there are 3.5 oz in 100 g. I boil 64 ounces of water = 2 L. That's 7 L boiled from a 100 g canister. Hmmm – where's my factor of 2 error?

[Rick M]

del

[James Marco]

Jerry, 8g/.8L was quoted as the lowest Roger gets at medium heat.

I was reducing his numbers a bit due to three things:
** a cone type setup(Roger doesn't use one)
** a heat exchanger pot(about 10% more efficient.)
** using LOW heat (Roger was using medium heat.)

I figure about 2g/L for all three items, roughly. I was hoping for 5-6g/Liter or .2oz/L but I don't think that will happen.

I get about 9g/L out of my SVEA with the same set up. I know that canister gas has a higher heat value than WG initially(before adding in the weight of the can,) but I am ignoring that. I am also ignoring the gram or two difference that is wasted during priming (I actually added that in when I measuered the SVEA because I used a midi-pump to start it, but the canster stove wouldn't require any priming.)

Anyway, max efficiency should be about 10-12 minutes to boil a liter with about 8g of isobutane/propane. I am sure it will not do WORSE than my SVEA. I get roughly 3-4 liters per ounce(average 9g/L.) If I am cooking meals, I figure two liters per day including 2 primings and simmering for about 15-20 minutes on one ounce of fuel. Hey, ha…I eat like two people when I am out…

[Jerry Adams]

Looking some more at Roger's articles, he talked about 9 g to boil 1 liter for Jetboil, 11.5 g for conventional upright, close to what you're saying. I assume his stove will be closer to 11.5 g since he has no heat exchanger. I bet some measurements will be posted at some point…

[Mark Fowler]

James – Why carry 2 x 100g canisters rather than a single 230g canister? 2 x 90g = 180g canister weight versus 135g. The weight saving more than covers the extra 30 grams of gas and extends your range by a day.

[Roger Caffin]

> I'm sure they would be IF that was the kind of detail that I wanted to know. But its
> just a stove. I really don't care about the minutiae of its operation and manufacturing

Heresy and blasphemy!!! :-)

> If its good, reviews will start popping up in other forums.

Only if I decide to sell it outside the BPL environment. That is not a given. This manufacturing thing is hard work!
Licensing to another manufacturer? Maybe one day.

Cheers

[Roger Caffin]

Hi all

I have previously shipped 8 of the stoves with the FMS-116T burner some time ago.

I am happy to report that the current batch of ~30 stoves have all been through their final burn test and been packed up into boxes. The back block is double thickness (ie 2 layers) and is for USA. The middle layer goes to Europe – we have quite a few European readers.
The front small group stays within Australia.

What boggles me is that I can buy 'little things' from ebay from Hong Kong for $2, and that includes packing and postage. How they do this is beyond me! The cardboard boxes cost nearly $1.40 each, plus there's bubble wrap and packaging tape. And you KNOW what the postage is like. (Does the Chinese gov't subsidise exports this way? Hum …)

Anyhow, most of the orders I have received so far are in this batch. A few of the latest ones missed out because I ran out of stove bodies. Sorry about that. But yes, I have all the other bits, so it's back to the mill for more stove bodies tomorrow.

Manufacturing & production is SO different from scientific research! My respect for the manufacturing industry goes up.

Cheers

[James Marco]

Roger,
I don't/can't do much winter camping any, so I can wait. Send mine along when you get the second batch done.
Thanks!

[James Marco]

Mark,
I have found that cannisters are generally unreliable. I have lost 2 in the one year that I tried them (back when the Coleman F1 was newly released.) Both had problems with the Lindal valves and emptied in my pack after using them. One was the older Coleman, the other was a Snow Peak. I have not heard of this happening in a couple years, though…not since they fixed the valves to be standard for all stoves. I hope it was a tollerance problem, hence fixed. But, I'll stick with two 4oz cans for the next year, even if they are heavier.

[James Marco]

"Looking some more at Roger's articles, he talked about 9 g to boil 1 liter for Jetboil, 11.5 g for conventional upright, close to what you're saying. I assume his stove will be closer to 11.5 g since he has no heat exchanger. I bet some measurements will be posted at some point…"

Yeah, well, heat exchangers are not a magic bullet. While I made several of the things, and still use one, their action is not well understood by most. Basically, they only extend the surface area (the heating surface) of a pot. Example, the ones I made were about 17% larger in surface area for a 5.25" grease pot pan. I get about 21.65 sqin of heatable pot bottom out of a standard grease pot. After adding the heat exchanger ridges, I get about 25.33 sqin.

But I only get about 15% faster heating given the same flame on both pots. Reducing the flame shows only a 10% decrease in heating times. Reducing the flame again shows only a 7% decrease in heating times. On very low it only shows about 5% (near the limit of my tests) decrease. With a tiny flame, I was getting 20-25 minute boils but didn't show any real difference (+-15 secs) over 5 runs. It starts to depend more on heat losses than heat absorbed.

Soo, what is happening here, is that the more efficient you set the flame height (very low is the best for fuel efficiency) the less well they work. Or you can think of the simplified corallory as they only work with excess heat. (Not quite true, but close enough for camping.)

JetBoils are not as efficient as alcohol stoves. Why? With a well placed heat screen, the sides of the pot as well as the bottom are used to heat water. A typical alcohol stove set-up always includes a good heat screen at least 50% up the sides. This is largly offset by the good heat exchanger JetBoil uses. It is about doubling the bottom heating surface area. But, putting these two things together, means the heat exchanger efficiency falls off as fuel efficiency goes up. Sort of a cache 22. You don't save enough by going to low heat to make it worth it since the heat exchanger efficiency drops off quickly, too…looks to be a curve.

Basically, I am planning on using the cannister stove as a heat source in a typical alcohol stove set-up. I am hoping to reduce the ammount of fuel required to boil 40F(4.5C) water to boiling (210F or ~99C) with about 5-6g of fuel under ideal conditions in a lab. This will mean a 20% increase in the field, or about 6-7g/L.
But, anything less than 9g/L would be acceptable, given the weight for two weeks at my usage. It MUST do better than my SVEA, or I will just drop it.

[Jerry Adams]

"Does the Chinese gov't subsidise exports this way? Hum …"

yeah

I've recently bought several things for less than $10 from China via amazon.com – portable MP3 charger, automobile cigarette lighter MP3 charger, and a wind speed meter. How do they do it?

And a couple scales with 0.1 g resolution. The first one broke. It's so cheap I don't care it'll probably break sometime.

[Jerry Adams]

That makes sense about heat exchanger – low flame will stay next to pot without heat exchanger so it makes less difference.

One thing is, if you go slowly, there will be more time to disipate heat so efficiency will go down. I wonder how much of a factor that is.

I made heat exchanger – accordian folded aluminum over the outside of the pot with channels about 1/4 inch high for the flame residual to flow through. 13.5 g/L w/o heat exchanger, 11.4 g/L with, 15% decrease. The 15% decrease is about the same as you said.

But my 13.5 g/L is a little larger than the number Roger measured 11.6 g/L. I used a Pocket Rocket which might be worse than average and I did it outside in the wilderness rather than a lab setting which might explain this?

If you could get less than 9 g/L that would be pretty good. Report back your results!

[James Klein]

James, care to show the details of your grease pot HTX ridges?

"Soo, what is happening here, is that the more efficient you set the flame height (very low is the best for fuel efficiency) the less well they work"
I agree – there are diminishing returns as burn rate decreases. Though it is still nice to have the extra margin for when you really want to warm water fast. I have trouble getting HTX pots to pay for themselves (in fuel savings) over what I'd use otherwise b/c they are all heavier gauge metal and tend to be narrow.

"JetBoils are not as efficient as alcohol stoves".
I can certainly boil water more efficiently in a HTX and cone setup with remote canister stove than with alcohol (1/3 less fuel require) (with water heatup rate, pot/cone setup, etc equal). I also see improvement by adding a cone the the HTX pot setup with cannister stove if heating fast enough, though, unless wind is involved in would lake a lot of boils for the windscreen to pay for itself in fuel savings.

"5-6g of fuel under ideal conditions in a lab. This will mean a 20% increase in the field, or about 6-7g/L".
It would take about ~400kJ to raise 1L of water 95C. To get 400kJ youd need about 9g of butane/iso/propane (@100% heat transfer efficiency). I could do the above with ~12grams fuel.

[James Klein]

Rick, I think you've gotten the details you were after but if not:

Roger made a remote canister setup (capable of inverted "winter" use). His can use either the Fire Maple 113t or 300t burners.
[EDIT: FMS-116T or FMS-300T – RNC]

-Finished weight is 80-90 grams – he quotes 80s but has since change the legs a little. This is about half the weight of any comparable off the shelf stove.
-It has a needle valve at the stove and an on/off valve on the cannister end.
-Small flexible fuel line
-Canister connector can handle typical canistor, powermax or campinggas.
-He has offered it for $125USD to bpl members in a limited production run. And, I think, has no specific plans to go commercial on this stove.

[James Marco]

"James, care to show the details of your grease pot HTX ridges? "
Well, it really doesn't belong here, but sure.
Hmmm, I don't have a current version pic, but I have a set of development pics. Here is one that shows the genesis.

The current version has 5 ridges at about 3/16 depth. The old three ridged version has about the same depth, but only helps about 11% overall. Sorry…I thought I had one.

As far as fuel usage goes, I was guessing I was bumping into max efficiency. I don't really care, since even flowing water is usually about 34-35F even if it has ice in it. 12g is a LOT of fuel, though. I may have to hope for 50F water when I am out just to hit 9g.

[Rick M]

del

[Roger Caffin]

Hi Rick

> Do you have to send a stove to Roger
No, I supply the whole thing, fully tested.

> If I become a BPL member, can I place an order
Yes. Use email addy below.

> and still expect to receive a stove before the New Year
Barring death and disaster, I would certainly think so.
Batches 1 & 2 have been shipped. I am now into batch 3.

Cheers
[email protected]

[Ryan P. Murphy]

My stove arrived today (actually it arrived Saturday but there was no one around to sign for it so I had to wait) and in my VERY limited bench testing I am impressed. It's ridiculously light for a remote canister stove; exactly how light I can't say because I don't have a scale. I really like the "spider" canister click system. There is something so satisfying about the sound of the canister clicking onto the attachment before actually sealing the connection. I was surprised that in liquid feed mode I can actually see fuel traveling through the fuel line. I will report further when I've done some real world testing. I'll be using it throughout the fall and winter in the Adirondacks and it will see some more serious winter use at altitude in Utah and Colorado in January. Beautiful work Roger. Now if only I could get my hands on one of your winter tunnel tents…

[Jon McConachie]

My stove arrived today and it is a work of art. 87g per my kitchen scale.
Thank you Roger.

[Roger Caffin]

> > and still expect to receive a stove before the New Year
> Barring death and disaster, I would certainly think so.
The X axis power driver on my CNC has suffered a slight misfunction and is away being repaired. This will create a delay of a few days in manufacturing.

No, 'slight misfunction' does not mean a catastrophic bang with smoke everywhere! It just means that the safety circuit started to trigger becasue of excess current draw at high speed. We know what the problem is likely to be – a damaged FET in the H-bridge.

Do not adjust your set, we will soon be back to your scheduled program.

Cheers

[James Marco]

Yup, mine arrived yesterday. I did some preliminary tests and was getting about 10-12g/L, with no tweaking. Weight was 86g.

[Jan Rezac]

Roger, thanks for perfect timing. The stove arrived last week just on the day I was leaving for a four-day trip. It was an opportunity to test it a bit, although we cooked mostly on fires.

The stove is very nice and light and the attention paid to some construction details is really amazing. I like it a lot.

However, I've encountered one quite serious issue: I was screwing the valve onto the canister and although the safety valve lever was in the "off" position, the gas started to leak. At first, I wanted to tighten it quickly to get a seal, but the leaking only increased so I disconnected the canister. It turned out that the brass pin was stuck in the "on" position, regardless of the position of the lever (which I previously turned to "on" for storage and switched to "off" just before use). I found that this can happen because the white body of the safety valve moves horizontally a couple of millimetres and when it is pushed into the valve assembly, the eccentric region is not aligned completely with the pin (see photo). As a result, the pin is caught on the edge of the full-diameter region of the white part, being engaged regardless of the position of the lever. Pulling the white part out a bit fixes the issue for the moment.

Since then, I was checking the pin before every use, and this problem occurred again once or twice. The design should be updated, most easily by making the eccentric region a bit wider to accommodate the possible shift, or by preventing the shifting movement by some other means. I will fix that myself on my stove; I will probably insert a spacer into the valve assembly so that the white part can not be pushed inwards any more.

Additionally, I would prefer to have the on and off positions of the lever to be left and right (with labels on the sides of the black block) rather than up and down. As it is now, the lever in the off position points outwards, and because its quite thin and sharp rod, I'm turning it down when I pack the stove. Being able to pack the stove as is would be nicer, because the stove will be ready (in off position) for next use.

[Jan Rezac]

I have just fixed the problem described in my post above. To prevent the safety valve (white part) from being pushed inside, I inserted a spacer that fills the small empty space between this part and the aluminium hose connector on the other end.

I cut a thin (1.4 mm) ring from a plastic tube of approximately right diameter. A piece of this thickness perfectly fills the empty space. To allow free flow of the gas from the outside into the ring, I cut several tiny notches into one face of it.

It works well, now the valve can not be moved into the position where the pin would be blocked.

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