Jetboil cold weather heat exchanger

[Jerry Adams]

The other thing that makes mostly empty canisters work less well is there’s less thermal mass because there’s less fuel.

To produce the same amount of heat to evaporate the fuel, the remaining liquid fuel will drop more temperature. The fuel will drop maybe 3 degree F in a full canister, but maybe 13 degree F in a mostly empty temperature, so the lowest ambient temperature you can get the canister to work at is about 10 degree F warmer for a mostly empty canister compared to a full canister.

[Bob Moulder]

Robert, great to hear about your mod and how well it worked!

It’s especially valuable — and a good confidence builder — to have the direct comparison with the other stoves in a real-world setting where breakfast is on the line, lol. :^)

The long-range, seasonal forecast predicts a ‘real’ winter this year and I hope to get up the Adirondacks for some seriously sub-zero field testing.

 

[Hikin’ Jim]

Bob,

Pretty cool HX strip.  I’m surprised that it didn’t overheat the canister in warm weather with an extended burn.  I guess it reached some kind of equilibrium.  I’d be really careful with a windscreen and the HX strip.

HJ

 

[Hikin’ Jim]

MSR tried that with their first version of the 110 gram IsoPro canister. When others came up with what is now the 110 g. canister standard, MSR couldn’t compete, so they wisely followed suit.. Their low/wide canister had so much more metal (thus heavier) than the Jetboil, Snow Peak, etc. versions. Also, the original MSR 4 oz. canister wouldn’t fit inside our smaller pots for transport.

@zia-grill-guy, I’m not sure if it was competition or not although I’m sure price was part of it.  MSR used to have a different vendor.  The canisters were a different shape, had different caps (flatter, no semi-detached pull tab), and were a duller red color.  They had their flat, wide canisters on the market for quite a number of years.  They switched to the “standard” 110g canister format when they came out with their one liter sized Reactor.  They wanted a canister to nest inside, so necessarily they had to go with the standard format.  I remember this distinctly because I wrote a review of the One Liter Reactor when it first came out.

I’d say it was probably a combination of factors:

1. The introduction of the one liter Reactor
2. Competition from the lighter weight standard canister format (why carry a heavier canister?).
3. A huge cost savings from Taeyang, the vendor to whom they switched, derived from using the same format as all the other major brands (except Coleman).

Changing the subject slightly, I’ve never seen Coleman canisters in anything less than “8 oz” size in the US.  However, I’ve seen photos of what appear to be “4 oz” sized canisters in the UK.  Go figure.

In Japan, I’ve seen some down right funky Coleman canisters that had what appears to be a 7/16ths thread but with a different TPI and a male tip.  The tip would dispense gas if bumped.  Far better to have the Epigas type standard 7/16 UNEF threaded connector with Lindal valve that are the common canister in the US, UK, Australia, and New Zealand (probably elsewhere too).

HJ

 

[James Marco]

Robert, you might try painting the strips with furnace paint (except the top and can contact.) This would likely add no more than a gram or two of weight and still add enough insulation to let you reduce the size of the middle portion of the strip by about 10%. You would end up with a net overall weight reduction. Though a round bar flattened at either end would also improve transfer efficiency and minimize surface area. Copper is pretty easy to flatten.

[Shelley C]

Any updates on this after using it (2 years later)

[Bob Moulder]

Works great.

I have not run into any issues and have had only positive reports from others who have used it. I am now using only the cheap butane table-top stove fuel and it works fine. I used to call it ‘straight’ or ‘pure’ butane but as others have pointed out it is a melange of various leftover hydrocarbons from the refining process, which is why it is so cheap.

David Thomas did some tests in Alaska well below 0°F and reported here and here.

[Kosta K]

Hi Bob,

It looks like it’s been a while since this thread has been updated, so I was wondering what your current setup looks like (I’m guessing you’ve continued to refine and tweak it).

Also, I was wondering what you thought of the idea of combining the copper heat exchanger with the water bath technique. I haven’t gotten a chance to try it  but I would think that the copper heat exchanger would warm the water which would uniformly warm the canister (instead of just one spot where the exchanger makes contact). I would think that this would also help with the issues you encountered with the larger size canisters.

[Kevin Babione]

Kosta,

Bob has taken a “hiatus” from BPL (since last December) so don’t expect a reply from him.  I’ve got a trip scheduled with him in a couple of weeks – I’ll try to remember to ask him about your idea and will post when we get back.

[Kosta K]

Thanks! I hadn’t realized that.

[Gary Dunckel]

Combining the Moulder Strip with a water bath is an interesting concept, Kosta. However, Bob and I have both settled upon employing a canister cozy. This might make it a bit more difficult to heat the water bath, and it certainly could make things a bit more messy, as well as slightly more complicated. As it is, Bob, David Thomas, and I have all had excellent performance at temperatures below 0* F. For my part, I don’t see any need to “gild the lily.” The copper strip solves everything.

Kevin, please say hi to Bob for me – and let him know that many of us miss him here on the forums…

[David Thomas]

Kosta, I’ve tested Moulder Strips down to -25F at home and then some of Gary’s and DavidG’s versions at -21F during a trip to Fairbanks. As Gary says, we have good enough, easy solutions down to stupid-cold temperatures.

So I don’t bother with water baths.  Sometimes I’ll apply a Bic lighter flame directly to the canister until it is warm enough to run and then let the Moulder sustain the canister’s temperature.  But in milder temps, without an MS, or with lousy butane, a water bath works fine.

A solid strip of copper is easiest, although carefully contoured aluminum can do it at a lower weight.

We vary the most on how we secure the Moulder Strip: thin Velcro strips as are sold to organize extension cords, wide Velcro that also serves as a cozy, silicone “LiveStrong” etc wristbands, or a neoprene band sewn from sheet neoprene or cut from the arm or leg of an old wet suit.  I’ve used all of those except the silicone bracelets and they all work fine.  Once sized correctly, the neoprene is the most secure*, functions as a great cozy, too, and neoprene’s burn point is 500F.  A cheap (free) source of neoprene are those soda/beer cozies given away as promotional items.

*and secure is nice at +10F and more so at -20F.  You’re doing most things in gloves and really want to minimize any fine, barehanded tasks.

[Kevin Babione]

Gary – I’ll pass on the message.  Even though I see him a couple of times a year for a hike or for breakfast (he lives a couple miles from my in-laws) I still miss his posts here too.

[JCH]

Kevin,  please give my best to Bob as well.  Really miss his insight and creativity, but fully understand his decision to take a break.

[Kosta K]

Thank you very much for all your help guys!

Once last question. I’ve read online that the Minimo suffers in windy conditions. What do you all do to compensate for that?

[David Thomas]

Cook on the ground instead of on a table or rock (right at the ground surface wind speed is zero).

Pile up rocks as a windbreak.

Prop your pack up as a windbreak.

Bring a piece of heavy duty aluminum foil or car window sunshade to wrap around the stove.

Bring / make a caldera-cone style conical pot support.

Cook in your tent.

If some camps might be really windy, have a few no-cook meals along (often a good idea for many reasons).

Accept that it may be less efficient and bring a bit more fuel.

[Kosta K]

Thanks for all the suggestions, guys!

I’ve ordered the parts, and look forward to starting this project and testing it out once temps drop a bit more…

[Alex]

Hey guys, I see that this thread is a bit old now but this seems like a good place to post this (sorry if it isn’t though).

 

A question here from Australia where our winters don’t really get all that cold, compared to what you guys get in North America. Camping in the snow in Aus, the minimum temperatures might hover between -1 C (30 F) and normally not below about – 10 C (14 F) on very cold nights.

 

Is the upper end of that temperature range too “warm” to use a copper heat exchanger on an upright canister stove?

[Jerry Adams]

No, not too warm.  Maybe 50 F or 70 F would be too warm?  I’m just grabbing numbers out of thin air.

On the other end, 14 F would be warm enough to use isobutane without any Mulder strip or anything.  It would be a little slow, especially if your canister was mostly empty.

[Kosta K]

If it’s over 5C (40F), you really don’t need the copper strip. However, it won’t make your tank too hot. A quick sanity check is just touch the canister a few cm away from the copper strip, and see if it’s hot to the touch. As long as it isn’t, you’re good to go!

[David Thomas]

At -10C (14F), a high flame on a marginal butane mix would be limiting and a Moulder Strip would solve that.  A few people refill with the cheaper butane (not mixed with propane nor containing iso-butane) from the horizontal canisters for use in a table-top stove and then you need to do something (Moulder Strip, water bath, flick your Bic) below about 5C (40F).

But near freezing?  I wouldn’t worry about a copper strip transmitting too much heat.  These canister  stoves are safe to use at 38C (100F) **without a copper strip** and you certainly aren’t getting the canister that warm using a copper strip in even mild winter conditions.

[Alex]

Thank you all for your helpful responses! I never expected a response so quick, let alone that many.

 

Next step is to make one of these copper strip devices

[James Marco]

Generally, copper or aluminum works with aluminum being the lightest and copper being best below -10C/14F. Initially, set the aluminum strip a little too far into the flame. It will melt to where it should be and leave a “rind” of rather thick aluminum right next to the flame. Aluminum has nearly as good heat conduction as copper and has less of a start up delay…it doesn’t “soak” up heat like copper does.

[Jerry Adams]

aluminum has half the conductivity so you need twice as thick a strip

and it weighs less than half as much – true gram weenies would use aluminum but the weight savings is insignificant

use whichever is the most convenient, just make sure and use the dimensions specified, if it’s too thin it won’t work as good

I tried Mulder strip on a tall stove – a Soto – it didn’t work very good

I tried Mulder strip on a short stove – a BRS 3000 – it works great

I don’t think this theory has been confirmed by anyone else, but it’s my experience.  Maybe there’s something else going on.

Anyway, if you have a tall stove and it doesn’t work very good, maybe that’s an explanation

[Author]

Posts