Wednesday, March 28, 2012

The Alpine BOMB for the MSR Reactor

Starved for adventure (I blame school for that one) and sleep deprived (again, school), Phil and I finished our last day of class for the semester and headed into the Uinta Mountains of Utah to try to climb a frozen waterfall and a frozen pile of choss, which is called Red Castle.  Red Castle is one of the most popular places in the Uintas for backpacking, but rarely does anybody venture in that area during the winter.  The main reason for this is that the road is only plowed to about 8 miles from the trailhead and then there is an additional 12 miles of hiking from the trailhead to Red Castle.  20 miles of skinning or snowshoeing is usually enough to keep sane people away.  Most climbers don't even go into that area because the only waterfall up there is about 70 feet tall and Red Castle is literally a pile of rocks held VERY LOOSELY together by mud.

Red Castle during the summer

Phil and I have never been accused of being very smart or sane, so we decided to give it a try.  It took two  very long days to hike into Red Castle pulling sleds.  Once in there, we decided to climb the waterfall (about WI4+) a few times but judged that attempting to climb Red Castle, being so far away from anything, would be dumb.  (A side note: Haunted by this experience, we went back during the summer to attempt a climb of one of the west faces of Red Castle.  We ended up bailing after about two pitches because the rock quality was so poor.  It was more like trying to climb hardened mud than actual rock)

This, believe it or not, is simply a long introduction to how I came to hate canister stoves for winter climbing.  On day three of our trip, I was trying to heat up some water with my Jetboil so that I could have a warm drink and dinner.  This stove normally takes about 3 minutes to boil 2 cups of water during the summer.  On this trip, it took about 25 minutes to melt snow and bring the water to a boil, and that was while swapping out warm canisters from my belay jacket.  I took me almost two hours to eat dinner, make some hot chocolate, and melt enough snow for the next day.  I was so frustrated!

I went home, ordered a Reactor, and pawned my Jetboil off to my brother (He mostly does summer stuff anyway).  I have found the Reactor to be far superior to the Jetboil when it comes to cold weather use, but it's still not perfect.  Though much more efficient than any other canister stove I know of, the canister still gets really cold and the stove doesn't work nearly as well as it could.

A friend of mine is headed to Denali in about a month.  To get ready for this trip, he and his climbing partner have been spending a lot of time this winter in the Tetons above 10k feet.  My friend told me that he was worried about his stove situation because his reactor wasn't working all that well in super cold conditions (-10 degrees or colder).  I told him I would try to help him come up with a solution.

Here's what I came up with:
After four hours of failure, this took about two minutes to make.

I will be making a closed-cell foam cozy for the canister.  The current cozy is just part of an old wool sock.  The sock isn't nearly as efficient as closed-cell foam and I am afraid that it could catch fire or melt if the copper gets too hot.

My original designs were much more complicated and involved copper tubing being pounded flat, then wrapping that around the pot, and attaching that to the canister.  Because of the way the Reactor is designed, I thought it would be too difficult to get the copper tubing under the pot and against the actual burner.  Stealing heat from the pot seemed like the only way.

Four hours of failure later, I pounded some copper tubing flat, bent it into a shape that would hug the silhouette of the stove, and stuck the pot on the stove.  Though the pot doesn't sit perfectly flat, it is hardly noticeable.  The copper piece now transfers heat from the stove to the canister to keep the canister warm.  I haven't tested this extensively, but so far so good.  The copper definitely transfers heat efficiently, potentially too efficiently.  The scary thing about Alpine BOMBs is that if the canister heats up too much, it will explode.  I will be testing this tool a bit more extensively next week.


As I test this system, I am constantly next to the stove, checking the canister to ensure that it doesn't get too warm.  This system was designed only to be used in extreme cold.

Also, because there were a couple sharp corners on the copper that I didn't sand down, I accidentally put a hole in my neoair mattress.  So, sand off the sharp edges.

I originally saw this idea on  He gave a thorough explanation of why canister stoves just don't work well in the cold.  The article is worth reading.  His Alpine BOMB looks like this:

I hope to have a little more information about the performance of the stove with and without the copper in a couple weeks.

05/18/2012 - It has been almost two months since I made the Reactor BOMB, but I've only had one chance to use it in cold weather.  This past week I used it on Mt. Rainier in about 25 degree F weather.  In the same weather without the copper heat exchanger, the canister would get very cold and the efficiency would drop immensely.  With one copper heat exchanger at about 25 degrees, the canister wouldn't get cold or hot and the efficiency would stay about normal.  It boiled 1.5 liters of ice cold water in about 3.5 minutes in 25 degree weather.  This is about the same amount of time that it takes during the summer.
I'm sure that another copper heat exchanger would be necessary to keep the canister warm if the temperatures were significantly colder, but one worked fine for the temperatures I used.  

The stove gets so hot that the copper turns black and becomes weaker.  I don't think the copper heat exchanger is going to be a very durable and with extended use it will eventually break.  Luckily, with practice, these exchangers only take about 5 or 10 minutes to make and don't cost very much.     


  1. If your situation is such that a canister stove just doesn't work, and you know it before hand, then a stove like an XGK would probably be better. I've used my Reactor in cold'ish weather (10 degrees) without issue and am confident in its capabilities but it took a little trial and error before I figured out how to keep it warm enough.

  2. Agreed. White gas stoves are always a pretty reliable option in the cold. I too have used my reactor in temps down to about 0 degrees without too much of a problem (though it was significantly less efficient). The issues came at about -10 to -20 degrees, and not with the stove but with the canister. The theory of the alpine BOMB is that it allows the stove to perform at -20 or colder as if it was much warmer because the canister stays warm and the pressure of the gas stays high. The danger comes when the pressure of the canister gets too high because it gets too warm. That's when you may have a real bomb on your hands.

  3. This inspired me to make what I call the "Alpine Halo" for my Reactor. My design is shaped like a halo. The ring nests in the recess around the burner where the lip on the pot's heat exchanger rests, and a strip carries heat down to the cartridge. It's harder to fabricate than a simple strip, but doesn't make the pot "tippy".

  4. Sounds cool, though tipsiness wasn't really an issue. The copper would get so hot that after just a couple days of using it, the copper would be in pretty bad shape and need to be replaced. Your's may work better, who knows. Worth a try.