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MSR Reactor Pot – 2.5 Liter

MSR Reactor 2.5 liter pot
MSR Reactor 2.5 liter pot

MSR Reactor Pot 2.5L

Heat Retention

Very Good

The MSR Reactor 2.5L Cook Pot has heat retention fins, a fold away handle, and a built-in lid colander to drain excess liquid. It's ideally sized for melting when married to an MSR Reactor Stove although it can also be used with other stove units.

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I became enamored with cook pots that include heat exchange fins this year after watching a friend melting snow with one last winter with far less fuel than me. This led to my changing my cook pot for this winter from an 1.3 liter ultralight titanium pot to a comparatively giant MSR Reactor 2.5 liter cook pot.

Though designed exclusively for use with the cult classic MSR Reactor isobutane powered stove, I’ve adapted the 13.3 ounce Reactor 2.5 liter pot for use with a liquid fuel stove, the tried and true MSR Whisperlite. The problem with the Reactor Stove, and isobutane stoves in general, is that they are not effective in temperatures under 20 degrees Fahrenheit, rendering them effectively useless for New England winter backpacking trips where nighttime temperatures are often below zero. Liquid fuel powered stoves are the only option if you need to cook and melt drink water in such cold weather.

Bottom Heat Exchanger Fins on an MSE Reactor 2.5 Liter Pot
Bottom Heat Exchanger Fins on a MSR Reactor 2.5 Liter Pot

The MSR Reactor 2.5 pot is built very differently from other pots with heat exchange fins. Instead of having an external flux ring under the pot, the Reactor fins are  enclosed inside a chamber that traps hot air against the sides of an inner pot, much like a double boiler stove-top system.

When coupled with a Reactor Stove, the Reactor pot and the stove are effectively windproof making for very efficient and fast boil ties. When coupled with an MSR Whisperlite, the pot and stove are less efficient and more prone to heat loss in the wind unless an exterior windscreen is used. Despite the resulting air gap between burner and pot, the Whisperlite quickly boils water in the Reactor 2.5 liter pot because the width of its gas jet is small enough to fit into the opening at the bottom of the Reactor Pot, enabling the heat it generates to be efficiently channeled up and into the pot’s interior heat retention chamber.

While I haven’t done any carefully timed measurements on boil time speeds (I leave that as an exercise for readers interested in doing that kind of testing), I can say that the combination of Whisperlite stove and Reactor pot boils water and melts snow much much faster and more efficiently, in terms of gas consumption, than my former stove and pot system.

Perhaps even more remarkable, is that the water in the pot will continue to boil even after it has been removed from the stove because the pot retains heat so well! Amazing. 

High Carbon Monoxide Levels

On the flip side, the head product guy at MSR tells me that the cool surface of the pot can influence the combustion of fuel from a liquid gas stove and cause it to become incomplete. This translates to more carbon monoxide, which can be fatal if you cook indoors or inside a closed shelter like a tent. In such a case, having a less hot flame would be better for efficiency and reduce carbon monoxide output.

Despite providing much better much better fuel efficiency, MSR has concluded that all heat exchanger pots generate more carbon monoxide when used with an open flame stove. However, the level of CO is significantly reduced if the 2.5 L pot is used with a Reactor Stove, which is why they are so adamant about it. As a reminder, no stove should ever be used in an enclosed space. Not to worry, I always melt snow in the wide open to avoid setting my tent on fire, carbon monoxide poisoning, or worse.

Collender built into the pot lid
Collender built into the pot lid


But one of the features I like the most about the Reactor 2.5 L pot is its packability, especially since I use a 66 liter pack which is on the small side for winter. I’ve found that I can pack the Whisperlite stove, pump, and a plastic cup inside the pot along with a pair of fleece gloves, so that the pot itself takes up minimal extra space in my pack. In those terms, this pot is even more packable than the smaller winter pot I used to use.

There are many other features of the Reactor Pot I like including the clear top lid – complete with collender holes – and its detachable fold and lock handle, since I detest pots that require a separate pot gripper.

If there’s one downside to using such a large pot, it’s the need to carry a separate cup to eat and drink with since holding the full pot is too hot to handle and eat out of. But the convenience and extra efficiency of the MSR Reactor 2.5 L pot for winter camping seals the deal for me. Let’s face it, if you have to sit around in winter for hours to eat and melt snow, you might as well carry a few more ounces and bring the best pot.

Disclaimer: Philip Werner (SectionHiker.com) received a complementary MSR 2.5 liter Reactor Pot and Whisperlite Stove for this review 

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  1. Very neat approach to the cold — I am interested to investigate if the Reactor pot might work similarly with a MSR Dragonfly stove.

  2. very interesting. A few quick reactions:
    1) true that the reactor stove is almost always out of the question at temperatures when snow melting is needed.
    2) but if you were willing to carry a shallow pan so the canister could sit in liquid water then cold temps are not an issue … but that IS a extra weight and fiddling
    3) Perhaps MSR could be convinced to offer a liquid feed inverted remote canister version of the reactor stove (ala the windpro). That would lower the stove’s viable temp range down into the 0-10 degree F range. OR even much lower temps if there was an an insulator for the canister and a way to hold liquid water in contact with the “dished” underside of the (inverted) canister
    4) But beware if you might use your setup in a well inclosed space (like a winter tent or hut). The reactor stove/pot combo tested quite well, producing low levels of carbon monoxide when running at full power like you would have with snow melting (less well at low power like simmering). But absent test results I fear the whisperlite/reactor pot combo might produce dangerous levels of CO (that is very often the outcome when flame contacts cold (cool actually) surfaces.

    • It probably bear repeating though…don’t use a liquid fuel stove in a tent because you can suffocate if you don’t kill yourself by burning down the tent around you first.

  3. HE (heat exchanger) pots are always more efficient for heating water. Unfortunatly the outer “heat trap” may be causing the stove to waste a lot of heat by deflecting it out along the outside. It will almost act like an insulator.

    A lower heat output is highly recomended with any stove, but especially when using HE pots. I think of the heat as a dynamic ball. The longer the “ball” is in contact with the pot, the better heat transfer you get. Raising the temperture of that “ball” raises the temperture of the ball, and reduces the time for heating, but increases the temperture and quantity of the exhaust gasses…ie. wasted heat. Slowing the heat production (turning the stove down) will help with efficiency, especially with an enclosed HE such as the MSR pot. Try putting your hand over the stove at a low setting and on high…a simple experiment that shows this increase. The lower setting will help alleviate JimC’s concern with CO by supplying more air to the flame (more complete combustion) and increasing the distance between the “cold” surface of the pot and the flame. It is unfortunate that the Whisperlite cannot run at about 2000BTU, stabily.

    Anyway, I would sugest a simple ti cone over the burner(under the pot) would help a lot with the combination. This would have the effect of concentrating output where it would do some good rather than along the outside.

    Anyway, This looks like an excelent combination for winter. Thanks!

    • I’m using a straight sized aluminum wind screen – removed to show the red hot glow of the stove. I like it better than the cone for winter since it lets more air into the stove, and I doubt that Trail Designs makes one for this pot.

      • Not quite what I meant. A smaller type heat concentrator just above the flame and below the stove, more flat than cone, might do fro a better description. It looks like the flame is outside of the heat exchanger on the pot, based on looking at your pics. Of couse, it would need to be Ti.

  4. Contrary to comments made above about the usefulness of the classic MSR Reactor Stove in snow melting temps, I’ve never had a problem using my Reactor stove at temps as low as
    -15F. I’ve also used it consistently at high altitudes (above 16K feet) and in heavy wind conditions. The trick is to keep the canister warm in a pocket near your body when the stove is not in use.

    In general, canister stoves are being used more commonly than ever before on climbs in the Andes and Himalaya.

    • John, I have friends who claim the same thing and I believe them. Problem is they claim they want to sell the idea to MSR and won’t tell me how they do it. Can I ask which fuel canister mix you use, what size canister, which pot size, how you insulate the bottom of the canister, and how long you can melt snow without reheating the canister? The Reactor burn is regulated pressure wise – so I assume you can get through the entire canister before it craps out. True? Do you also bring liquid fuel stoves with you as backups?

  5. Phillip,

    I use the standard 8oz Isopro cannisters made by MSR and just the standard pot that comes with the Reactor stove. As I mentioned, in cold weather, I carry a cannister or two in a pocket next to my body while I’m climbing or hiking. When I set up the stove, I place the cannister in the bottom part of a water bottle insulator that I cut in half for that purpose. While I’m using one cannister, I keep the spare(s) warm either by wrapping them in clothes or stashing them in the bottom of my sleeping bag. In very cold weather, I’ve sometimes had to change out a cannister for a spare before it emptied. I don’t bring a liquid fuel stove along. In my view, any possible hassle with keeping cannisters warm is worth avoiding flare ups and fires from liquid fuel.

    • I’ll give that a try sometime. Have to yogi a Reactor from somewhere :-)

    • I would bet that the only canister stoves that are being used for high elevation hikes are the Reactor and the Soto OD-R1 stoves because they have regulators in them that keep the gas in the canister flowing at a steady rate instead of being dependent on how much gas is left in the canister.

      • I’ve recently purchased the Soto OD-R1X (Windmaster) and have looked everywhere online to see if the MSR Reactor is compatible with other stoves. This is the first mention I’ve come across!! So now I’m wondering how stable the pot can be on the windmaster and are there any other considerations to worry about? Also if I want to use a remote stand with the Soto OD-R1X, who makes these now? So hard to find!

      • It’s a pot, so it’s compatible with any stove. I have a windmaster, but the 2.5 liter pot is probably wobbly on that. You probably want the “other” pot stand that Soto makes it. Good luck finding it. You’ll probably have to go to Soto direct. What’s this about a remote stand? I have no idea what you mean. Pls ask again but use different words.

      • Hi Philip,

        I can’t recall now where it was that I read it, but i read that the pot would not work with other stoves and that it could potentially damage the pot if used with something other than the MSR Reactor stove system. This was why I asked. Also I have the Soto Windmaster with the 4plex extended pot holder so I guess it would be pretty stable on it.

        As for the remote canister stand, Brunton used to sell one. The setup allowed for the stove portion (in this case the Soto Windmaster) to be attached to a separate stand instead of directly on top of a canister as usual. The stand is connected to a hose that connects to the canister, which in this setup would be safely away from the stove in a windscreen setup. This method I’ve read is recommended when putting a windscreen around the stove because in a normal setup (i.e. stove screwed into canister) the reflected heat from the windscreen could cause the canister to explode.

        Looking it up online the last time a Brunton Remote Stove Stand was available was in 2010 and has since been discontinued. Wondering it anyone else knows where to find something similar!

        Thanks! :)

      • MSR warns people about using the Reactor pots with other stoves because it creates “more” Co2. Liability stuff. Ignore it at your own peril. :-)

        Take a look at the MSR WindPo II. It has a remote canister config like your looking for.


      • Thanks for letting me know. It’s a shame though that there aren’t more remote stands available on the market that I can use my Soto Windmaster with. Not really in the mood for buying another stove though!! (Yet!) :P

      • Another question: do you ever cook with this pot, or simply use it to melt snow? I plan on using this setup to cook, sauté and maybe fry stuff in it. Does it have a sufficiently good non-stick property from being hard anodized? :)

      • I have just melted snow with in and boiled water, but don’t see why you couldn’t do anything with it.

    • John’s tactic works. but we’re dealing with a complex situation here with multiple factors opposing each other. I’m not gonna try to give a complete explanation because I’ll botch it but here is pretty much what happens.

      Many kinds of canister fuel … propane, n-butane and iso-butane are the most common for our use. Most contain a mixture of propane and one of the butanes. Canisters do not work when the fuel’s temp is less than it’s boiling point.

      At sea level propane boils at -43.6F, n-butane boils at +30.2F and iso-butane boils at +10.9F. Mixtures boil at a temp between the boiling points of the two fuels in the mix and the boiling point shifts as you vary the proportions of each fuel.

      John’s MSR fuel cans are a mixture of propane and iso-butane … much better than propane and n-butane for cold weather use.

      As a mixture boils the vapor will not contain it’s components in the same proportion as they exist in the liquid. The vapor will contain more of the component with the lower boiling point. The result is that the propane get’s used up faster than the iso-butane and the boiling point of the changing mixture increases. That explains John’s observation “I’ve sometimes had to change out a cannister for a spare before it emptied” … he’s running out of propane.

      Stoves that can use inverted canisters (MSR WindPro, for example) only need the canister pressurized enough to feed the liquid mixture to the stove where it is vaporized at high temps, well above the boiling point. They work if the temp of the liquid mixture is at least a little above the mixture’s boiling point. The liquid fuel leaving the inverted can leaves at the same proportions of fuel in the can and the proportions in the can does not change over time. They can use the entire contents of the can.

      Another factor is altitude. Boiling points of liquids DEcrease as altitudes INcrease. So John’s experience at 16k feet will be different than Phillip’s at 4k feet. John’s Reactor stove will get fuel at temps that below those where Phillip’s will fail.

  6. Nice pot, but with a price tag around $90, I think I will just carry a little extra fuel.

  7. Nice overview, I agree that HE pots are worthwhile in very cold temps and when melting snow. What’s the exact weight of the pot with nothing else (no lid, colander/bowl, grabber, etc.)? Easy to replace the lid with a very light Ti foil lid.

  8. for hi altitude keep the canister warm e.g. at 8,000 metres plus, keep the canister inside your jacket. when cooking heat up a flat rock or find another method of keeping the canister above -7 degrees Celsius (20F) otherwise you will go hungry. That is the nature of physics and the simple solution because this cooker boils water so quickly is that you should slip the canister into your pocket an hour before making camp over 4,000 metres. This lesson was learned the hard way and I would not make this mistake again! This stove however is awesome!!!!

  9. Hi,

    I’ve thoroughly enjoyed your blog and its gear reviews from the shadows for quite some time now. Perhaps it’s s time to finally step forth and field a query your way:

    Did you experience any quenching/extinguishing of your Whisperlite’s flame when you put the reactor pot down on the stove’s pot stands?

    I have two Reactor pots (1.0 L & 1.7 L) and just recently purchased the Primus Omnilite Ti. Instead of shelling out for Primus’ heat exchange pots, I’m considering making do with my two existing Reactor pots – as well as purchasing the Reactor 2.5 L pot. With such idea in mind, I proceeded to test my two Reactor pots with my MSR MicroRocket (no problems, with indoor boil times on par with the Reactor stove). However when I tested the Reactor pots with the Omnifuel Ti (using an MSR gas canister) I repeatedly experienced a quenching/extinguishing of the stove’s flame when I set the Reactor pots on the pot stands. Often the flame shrank suddenly in intensity as if the pot sucked the life out of the flame, and then the flame suddenly died.

    Do you recollect any such issue?

  10. hmm. Never tried that combination. Sounds like you aren’t getting enough air in or you’ve simply run out of fuel.

  11. Yes, I did my testing with some near empty MSR canisters I had kicking around.

    I picked up some white gas (Primus Power Gas) today for the OmniLite and ordered the 2.5 L Reactor pot (making my Reactor pot collection compulsively complete. I’ll run some tests next week comparing boil times for the 3 reactor pots and a couple other pots (incl. Primus’ own heat exchanging pot(s)–all on the Omnilite/Multifuelstove and MSR Micro Rocket. If it’s not considered annoying then I’ll post a very brief summary of the test’s general results here.

    I did a couple of Google searches on experiences of combining Reactor pots w/ other stoves but came up basically empty handed, your posting (and two othe cursory mentions) aside. Surprising, me thought.

    My wife gave me thoroughly quizzical looks when she caught me doing my initial Reactor + Omnifuel test the other day. Next week could see her taking steps to get me committed.

    PPS Your review of Patagonia’s R1 Hoody was the final drop that convinced me to purchase the piece. It’s nice but I find its stink factor a major detriment to the degree that after a few days it reeks and infests my so-called puffies (down & synth) with its stench. Such pieces are a major hassle to wash as regularly as the R1 demands, ergo its become a one-day outing piece for me.


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