MSR Reactor, Gear Test

Some of you may have seen the MSR Reactor tested over at Hendrik Morkel’s blog, Hiking in Finland and it’s thanks to Hendrik that I’ve had the opportunity to try the MSR Reactor myself as he made it available to other bloggers on the basis that they had it for 2 weeks before sending it on to someone else.

I hadn’t previously tried this stove system although I did own a Jetboil PCS which I eventually sold and while I haven’t tried the Primus Eta Express I have tried the 1.0l Eta Power pot. Neither the Jetboil nor the Eta Power pot impressed me, both failed to achieve anything like the advertised performance. The Reactor interested me though as the burner head is quite a unique design as it matches the diameter of the pot almost exactly, MSR also claim that the valve/regulator is designed so that the performance stays pretty much the same regardless of the amount of fuel remaining in the cartridge. I’ve previously found that the performance of gas stoves drops off significantly once the cartridge is less than ½ full even on the Jetboil.

You could be forgiven for thinking that the idea of using a heat exchanger was introduced by Jetboil or Primus but you’d be wrong, MSR were in fact working with heat exchangers as long ago as the late 1980’s with what was then known as the XPD Heat Exchanger.



A Scan of a Flyer I Recieved 1989-90

The heat exchanger was basically an adjustable corrugated sleeve that fitted around the outside of one of their standard pots in an attempt to reduce heat loss, an improvement in efficiency of up to 25% was claimed. I never actually used one but they were still listed on the MSR website last year and are still available from some retailers.


Unlike Jetboil and Primus MSR only have one stove using the heat exchanger although for 2010 they have released an additional 2.5l pot which is designed to be used with the Reactor, unfortunately they haven’t as yet released a sub 1.0l pot for solo use. The Reactor is quite heavy compared to a basic top mounted cartridge stove and basic pot combination, the listed weight is minimum 515g although I weighed the one I’m testing and it comes in at 486g including cleaning cloth which makes it a few grams lighter than the Jetboil I had. Like the Primus Eta Express it can hold a 220g gas cartridge, the Jetboil can only hold a 100g cartridge and with a cartridge and the burner stored in the Reactor’s 1.5l pot there’s still room for a few extra items. I found that I could store a 100g cartridge in a Tibetan titanium 550ml pot place it in the Reactor and still manage to fit the burner in.


Information Regarding Suggested Performance

My 1st impression on receiving the Reactor was positive as the information on the packaging is quite clear about the conditions that MSR test the stove in, they also give an indication of the performance you can expect in a variety of real world conditions. This is something I haven’t seen before; most manufacturers simply give the time taken to boil a given amount of water, usually 1.0l but with no mention of the test conditions.


Unique Burner Design and Easy to Use Valve

The burner is a pretty unique design and is reasonably quiet in operation, the flame is quite soft but after about 20 seconds the entire burner mesh glows red and the sound of the stove changes slightly. There isn’t a Piezo igniter which some will take issue with but to be honest I‘ve removed igniters in the past to save weight. The valve has a short distance of travel, about 1 and ¾ turns and has a good sized plastic grip which fold flat for storage.


Heat Exchanger, The Welds are Extremely Uniform and the Build Quality Excellent.


Measure Marks, Maximum Recommended Quantity 1.0l

The Reactor comes with a 1.5l pot which incorporates a heat exchanger and windshield, the maximum fill level is marked at 1.0l but it should be possible to use the 1.5l capacity as there is about 15mm to spare. The pot comes with a clear plastic lid which is said to be Heat-Resistant although I wouldn’t want to get it too close to the burner. There’s a flexible rubber knob on the lid which prevents you getting burned when lifting it off. The handle and means of keeping the lid firmly fixed to the pot for storage is quite clever, there’s a small length of stainless braided wire with a ball end which locks into a slot on the foldable handle. The handle itself locks in the open position and stays cool even at full boil. I’m not sure if a stuff sack is supplied, I didn’t receive one and there’s no mention of it on the packaging, it did however come with a small cleaning/drying cloth. The standard of finish was very good with extremely neat welds where the heat exchanger is welded to the pot.


Clear Plastic Lid and Rubber Knob, The Lid also Has a Single Vent


Clever Method of Securing the Lid


Handle Locked in Position

The 1st test was conducted in my garage using a new 100g cartridge simply to provide a comparison with previous stove tests. I weighed the cartridge before starting, used 500ml of water at 17°c and timed how long it took to bring the water to 99°c, I need to point out that the water was 10°c colder in some of the previous tests. The cartridge was then weighed to establish how much gas had been used. The stove was used at maximum output and the result was certainly impressive, it took 1min 55secs to reach 99°c and used 7g of gas.



Of course the real test is in real world conditions, the MSR doesn’t have a separate windshield although to be honest it doesn’t look like it needs one as the flame can’t be seen once the pot is placed on the burner. The only place wind could enter is via the small air holes around the burner head or via the exhaust vents around the base of the pot just above the heat exchanger but I was pretty confidant that the performance wouldn't be affected too much. The only area that I felt heat could be lost was the pot itself.

I tested the Reactor again, this time outdoors just prior to testing the GoSystem Fly (ti). Once again the results were very good indeed with 500ml of water (16°c) brought to a boil in 1 min 42secs using 7g of gas. The result was surprisingly better than the indoors test.



I’ve found that most basic stoves aren’t fuel efficient at maximum output as it depends on the pot used whether the heat produced by the stove is being absorbed by the pot or whether it’s being wasted either due to the flame pattern being wider than the pot or the pot simply being unable to absorb the heat at the same rate as the stove produces it. To gauge the efficiency of the Reactor at full power I tested it again with the valve open 1 full turn rather than the maximum 1 ¾ turns. As it turned out the stove used exactly the same amount of gas although the boil time was as expected, slower. This suggests that the pot matches the burner almost perfectly which is a very good result indeed. An additional test was with an almost empty 100g cartridge. With only 10g of gas remaining I repeated the previous test but once again the Reactor performed very well indeed, using 6g of gas with a slightly increased boil time, clearly MSR have somehow managed to regulate the pressure so that there’s minimal difference whether the cartridge is full or almost empty. With a 100g cartridge I would expect to be able to boil about 8.0L of water, easily enough for one week’s solo use with no appreciable drop in performance as the gas is used.

As far as performance is concerned the MSR Reactor performed really well but usability can only really be assessed while actually out on the hill so a wild camp is on the agenda.

So far the performance of the MSR Reactor has been excellent, as has been the efficiency and based on my experience I’d certainly recommend it over the Jetboil and Eta Power pots to anyone who needs a fuel efficient fast boiling stove. It’s heavy but if you consider that a 100g cartridge could easily last for 1 weeks solo use the weight becomes more bearable. The efficiency is good enough to make it useable for 2 people and it compares favourably weight wise with both the Eta Express and the Jetboil PCS.

The question is would I actually buy one? to be honest I’m not sure. The combined weight of a cooking system based around the Reactor including a mug, spoon, cozy, lighter and 100g gas cartridge would be around 750g. The 100g cartridge would allow me to boil about 8.0l of water. My current meths set-up, See Here including windshield spoon, mug, lighter and cozies etc weighs 172g and to boil 8.0l of water I’d need to carry 400ml of meths which would weigh around 400g bottled for a total weight of 572g. As my trips are usually only 1 nighters I only carry 100ml of fuel so the weight of my current set-up including fuel is only 272g. If I was making regular week long trips the ease of use and fast boil times might just make the 200g and the £125 asking price worthwhile. In truth I can’t afford to spend £125 on the Reactor although I feel it's worth it and undoubtedly I’d like one if only because I admire what I see as a genuinely good product that fully lives up to the manufacturers claims. If MSR were to release a Reactor downsized to suit a 100g cartridge rather than a 220g cartridge with a subsequent reduction in weight but while still maintaining the performance/efficiency then I’d buy it and sell off all my other gas stoves and quite possibly my multi fuel ones as well.



Compared to a Basic Stove Set-Up