Roger Caffin's Sub 90g Remote Canister Winter Stoves

[Maelgwn]

Are there any problems with the hose twisting akwardly? As you would light it with the canister upright and then invert - does the hose get twisted? My windpro hose gets twisted enough to topple to stove over when you take the pot off - I am guessing Roger has solved this?

[Franco]

The hose turns where it connects with the burner...

[Mountain Rocket]

The hose turns where it connects with the burner...

One of the benefits of using a lighter gauge hose

[rcaffin]

The hose turns where it connects with the burner...

Actually, the hose can rotate at both the stove end and the canister end.

Yes, I solved the problem I was having with the tripod legs, and all stoves are supplied with the final design.

Why two valves? The one at the stove is for fine control on the GAS flow (not on a liquid flow). That is fast and simple to handle. The one on the canister is a safety on/off valve. In the off position no gas can come out anywhere.

As noted elsewhere, the stove can use the standard screw-thread canisters, the French Campingaz ones (which are sold here in Oz), and the rather nice Coleman Powermax canisters.

Cheers
roger@backpackinglight.com

[Franco]

the hose can rotate at both the stove end and the canister end
Yes, it can...

I finally unpacked my stuff so had the opportunity to fire up the stove.
Sorry I did not bother to read those instructions again but were not needed as I already knew how to do it.
Pretty intuitive so no drama there.
I tested the inverted (liquid feed) set up and that was also very easy to do and worked like a charm.
After having turned on the stove on a medium setting for about 10 seconds I turned the canister.
No strange noises,splattering or stuff like that, the flame just kept going.
Now all I need is a trip to the snow.

[Mountain Rocket]

Here are some crap photos I took with my phone whilst playing around with the stove earlier in the week.

I look forward to the testing it out properly next winter

[icefest]

Dude, those photos are huge...
Now I really want one.. we'll see how long I can procrastinate buying one.

[KANANGRABOYD]

I have received the Roger Caffin stove.
90g on my scale.(could be 88 to 92 g...)
Looks very well made and can hold a 2L pot.
I am about to move house so my stuff is packed up , because of that tests will have to wait.
Note that just like with my Kovea you need to make sure that the arms are correctly folded out.
One at random tends to fold in as you move it about.

oHHHHHHHHH,
Well will have to jump on the bandwagon too.
I love stoves just as much as Franco loves pillows!!!!

[Franco]

pillows ?

[KANANGRABOYD]

pillows ?

Yeah I remember seeing a post of yours with a million pillows - i think on BPL?....lol!

[sim1oz]

Used our new Caffin stove in the snow at Mt Stirling a few weeks ago and it worked like a charm. So excited about it that I forgot to take photos...

[rcaffin]

Do you know if they are the 'improved' new legs Franco?

Yes, they are the 'new improved' legs. They work well.

I have shipped the first batch with FMS-116T burners. The next (and much larger) batch with FMS-300T burners is nearly complete. It got delayed by 3+ weeks of flu.

Cheers
Roger

[north-north-west]

I'm not a stove freak, but I really want one of those. Just wish I could afford it . . .

[sim1oz]

Can't afford it but bought one anyway

[Scott McPherson]

Roger,

I've been impressed with your remote canister stove project. I'm a hopeless outdoor gear DIYer/tinkerer and your stove design and the process you've gone through is very inspiring!

It seems that the design is successful according to a number of tests from users but I've got a couple of comments/queries after reading through the forums here and on BPL. I guess this may already be answered elsewhere but I didn't find it so maybe others have the same questions.
I see the heat fin that pokes up is designed to heat up the fuel line at the base to around 50 degrees C. How does this comparatively low temp increase work when other designs actually place the gas tube in the flame to a much higher temp? What's the difference in performance between the stove when sitting upright and inverted considering the heated fins effect is constant? The remote canister stove seems to be unique due to the multi-fit attachment and the burner based flame adjustment. Apart from that what else makes your stove unique compared to the current best remote canister stoves.

My last question is if they're still available to be bought in Australia?

Thanks,
Scott

[icefest]

Scott:
Most of your questions answers are available in the links I posted below.

It only needs 50°C as butane boils at ~0°C. Others have either been designed for multiple fuel use or have just kept using older designs.
The main difference with inverted stoves is cold weather performance. The propane doesn't boil off too early.

What makes it unique? Well it weighs about half of the next best stove.

Read these pages for more detail on the answers:
http://www.bushwalking.org.au/FAQ/MyStove1.htm
http://www.bushwalking.org.au/FAQ/FAQ_Efficiency.htm
http://www.bushwalking.org.au/FAQ/FAQ_Mixtures.htm
http://www.bushwalking.org.au/FAQ/FAQ_GasStoves.htm

[Scott McPherson]

Hi Icefest,

I understand the boiling points of these gases and the difficulties in fully utilising the fuel. It seems a bit much to expect the gas quickly passing thru a small 50°C chamber to be lifted in temp much at all to make a significant difference. In the links you added there isn't any data to show the actual temp of the gas exiting the nozzle with and without the heated fin... but that would be a bit tricky to test although not impossible. Those other possibly outdated designs are dealing with temps probably 5 to 10 times higher and most seem to work acceptably. I just wondered if other parts of the design are assisting the non spluttering burning but from what you say the only other unique feature is the weight which I have to say disappoints me as I thought there was something more sophisticated happening to produce so much interest in the stove... I'm sure intelligent design and material choices will quickly overtake the 90 grams set here as the other stoves really aren't too far off this.

I am looking to upgrade from my upright bottle gas stove to an inverted bottle gas stove but I'm just not sold yet on Roger's stove. Don't take my questions as a criticism as I am significantly impressed with his project so far. This discussion might be mute though as I don't know if Roger is still making the stoves.

Thanks,
Scott

[icefest]

Please tell me if I'm being too direct.

It seems a bit much to expect the gas quickly passing thru a small 50°C chamber to be lifted in temp much at all to make a significant difference.

Here is a quote from the pages I linked you . I have added emphasis to the part that answers your first question.

Not visible in the photo are the details inside the heat exchanger section. Obviously there's a hole going through the heat exchanger section from the connector socket to the needle valve seat, and the hole is large enough that liquid fuel can get through to the jet. Actually, it has to be somewhat larger than needed in order that it can be drilled on a production basis. Very long thin drills are very expensive and break easily. Getting the broken drill bit out is ... difficult. But you don't want the fuel rocketing down the middle of this hole and not getting enough heat pumped in for full vaporisation. How or why that happens was discussed in the previous Parts of this article. When it happens you get drops of liquid fuel coming out the jet and much spluttering of the flame. That's both dangerous and inefficient. So the hole is partly filled with an aluminium rod (Heat Exchanger #1) down the middle and the fuel is spread out into a thin layer between the rod and the inner walls of the hole. Heat transfer into this thin film of fuel is good. Trying to run the stove without this part of the heat exchanger in place is definitely not good.

Not shown in any of the photos here is a length of copper wire (Heat Exchanger #2) which goes up inside the PFA hose. This takes heat from the stove body up the hose to pre-warm the fuel, and is in addition to bit of aluminium rod. Actually, this tiny bit of esoteric design is reminiscent of the long brass rod in the fuel line of the Coleman Xtreme stove. Many have wondered what it is for. By now its function may be obvious: in addition to just acting as a filler, it acts as a fuel spreader and heat exchanger. But Coleman very carefully never explained it.

In the links you added there isn't any data to show the actual temp of the gas exiting the nozzle with and without the heated fin... but that would be a bit tricky to test although not impossible.

Why do you want to test this?
I'm sure you know how bad Ti is at conducting heat. This means there is little heat moved down to the jet via the stove stem. At the jet there are two thing happening, expansion and phase change. Both are endothermic. At 0°C, there is not enough energy to evaporate the fuel fast enough at sea level. With a gas feed stove the heat same heat much be applied to the canister instead.

Those other possibly outdated designs are dealing with temps probably 5 to 10 times higher and most seem to work acceptably.

Yes, they weigh pretty much double though. Just because a Optimus Svea works acceptably doesn't mean it is the best design or can be improved on. It's overkill. It's like using a bulletproof 1L drinkbottle that can survive re-entry for a day walk along the beach.

I just wondered if other parts of the design are assisting the non spluttering burning but from what you say the only other unique feature is the weight which I have to say disappoints me as I thought there was something more sophisticated happening to produce so much interest in the stove... I'm sure intelligent design and material choices will quickly overtake the 90 grams set here as the other stoves really aren't too far off this.

You have read the three pages detailing the making of the stove, right? If that is not intelligent design and material choices I don't know what is.
Can you tell me what stove is not too far off this?
I'm sure that everyone would welcome you making a lighter and better stove, I'll be happy to help beta test .

I am looking to upgrade from my upright bottle gas stove to an inverted bottle gas stove but I'm just not sold yet on Roger's stove. Don't take my questions as a criticism as I am significantly impressed with his project so far. This discussion might be mute though as I don't know if Roger is still making the stoves.

Why do you want to change?
On the last page of Rogers stove pages is his email address. Shoot him a message to see if he is still making them.

[Scott McPherson]

I appreciate you taking the time to reply to my query and I have gained some additional info from you but with all due respect Icefest, I did put my original question to Roger in the hope that he would answer the question with his expert knowledge of the system. I could have emailed him directly but thought there may be others who have an interest in his answers.

[Mark F]

The main issue is that most stoves work when vapourised fuel is ejected through a jet and ignited. So how to get a gas from fuel stored in a liquid state - heat the fuel to above its boiling point or reduce the pressure so its boiling point is below the temperature of the stove/canister body. Kero/shellite and invertable gas stoves take the first option while upright canister stoves take the send route.

I believe the key to understanding why the relatively low level of heat conduction on the Caffin stove using the Al bar works while many others run the fuel line through the flame is a product of history. The fuel line through the flame models originated with kero/shellite fuel stoves. These fuels require far higher temperatures to vapourise compared to butane (including isobutane and propane). The heated fuel line worked for butane as well, so stove makers continued to use it without further thought or experimentation. As gas stoves became more popular people found that a simple heat shunt (a bit of copper wire taking heat from the flame to the canister) could keep a butane canister working well below the air temperatures that would normally be the operational limit. Roger has picked up on this and formalised a heat shunt into his design no doubt helping to lower the weight in the process. This design is far less likely to work(I won't say cannot) with higher molecular weight fuels with correspondingly higher boiling points because of the increased heating needed for vapourisation.

I should declare that I own a Caffin stove (batch 3) and while I have not had the opportunity to use it in very cold conditions it works very well and it is now my first choice for most uses.

[Scott McPherson]

I did end up emailing Roger and he gave me answers about how the stove works in regard to the how the heat fin functions and also what changes he's made to the design to improve on the base fire maple stove. I'm confident now that his stove will meet my needs though I'll have to wait though as his cnc machine is on the fritz for a while.

[icefest]

I'll have to wait though as his cnc machine is on the fritz for a while.

Again?!

Last time he has to rewire it himself, IIRC.

[sim1oz]

Forgot to take photos last year, so here are some of a Caffin stove in action at the snow. Lake Mountain had no wind today so no need for a wind shield. Worked beautifully! Delicious hot lunch off the trail.

Canister upright after stove being lit

Liquid feed

[sim1oz]

Roger pointed out to me that I didn't have the valve to the gas canister fully open in the photo above. I was a bit distracted by excited kids enjoying their first play in the snow...

[Mountain Rocket]

Roger seems to have published a new article about the stoves. I no longer have a paid BPL account but if someone wants to PM me a pdf version of the article that would be fantastic

[Mountain Rocket]

Scratch that above request. Got the article now
Interesting reading. Mine has become blocked, need to do something about that.

[sherpa]

I'm considering buying this little stove, if I do, it will be my first gas canister stove. Before I go ahead I'd love to hear from anyone who has really put this stove through its paces, ideally in an alpine or low temp. environment. What are your thoughts/verdict? Have you discovered any inherent problems/foibles? Any issues with maintenance and repairs?, etc, etc.
Initially I was looking at the sit on top "pocket rocket" style stove until I discovered their poor performance in low temps. Then Robert introduced me, via this thread, to a little sub 90g remote canister gas stove. It was love at first sight! Robert, did Roger's latest article touch upon any of my questions?
Thanks in advance.
S

[icefest]

I'm not sure if it's been made clear in this thread, but the Caffin stoves are beta-products. They have their idiosyncrasies. That being said, I'm really happy with mine, and gladly am a little more careful with it.

[Maelgwn]

Sherpa - have you seen the MSR Windpro II? It does most of the things that Rogers does at a ok weight and is a "proven" product.

OR if you are really a weight weenie and don't need a stove in snow/winter conditions often you can make do by keeping the canister warm in your jacket/small bowl of luke warm water.

[sherpa]

Thanks!
Yes, fully understand the Caffin stoves are in a beta stage of development. Hence my questions. I had imagined that after a year or more of in field use, certain issues may have arrisen that may require further developing, testing or tweeking. Are users aware of any of these? Would it be best waiting for a full production model? I had also thought it may be possible to still buy on of these preproduction models. Am I mistaken?
Hi Maelgwn, I'm aware of the windpro but have not used one. I'll definitely give it some consideration should I choose to go down the gas canister path.
S