The thing about camping stoves is that quite a lot of the energy from that little gas canister you’ve carried up the hill is blown away by any breeze, or licks up the side of the pan instead of heating the bottom. Innovations in heat-exchangers, as seen in the likes of a Jetboil or a Primus ETA Solo have helped a lot with efficiency, but the MSR Reactor stove goes one giant leap further by integrating a pot and burner into one almost-seamless system.
Significantly larger in diameter than a Jetboil Flash, the Reactor’s pot holds 1 litre of water, but has markings on it for 1.5 litres. The pot has a max fill line at 1 litre which leaves half its height for, presumably, boiling bubbles. I suspect that MSR is being cautious here because any spillage could put out the burner. (?) The pot is pretty heavy, being made in a thick material with a pretty weighty heat-exchanger welded on to the bottom, and it forms part of the cooking system. You could not use the reactor burner with any other pot since it sits snugly inside the base of its own pot and blocks out any effects from wind.
The burner itself is wide in diameter (same diameter as a Jetboil Flash cup) and looks unlike most other burners. It has a metal grid which sits above a sort of sponge. Gas from your canister dissipates through the sponge and ignites creating a fairly even spread of very intense heat which makes the metal grid glow fiercely. You them place your pot directly on to this grid.
The Reactor boils water faster than any other stove I’ve tested. I ran a direct comparison with a Jetboil Flash, using the same gas canister and same water source. The Reactor boiled 0.5L of water in 1m46s. The Jetboil took 3m50s. That is mightily impressive.
Lighting it, however, is a little bit of a pain. The Reactor doesn’t have an in-built ignition, and my first attempt at lighting it – using the Piezo ignition pen from an MSR MicroRocket – resulted in a WOFF of gas and me losing all the hairs from my right hand (yes, really). Once the smell of burnt hair had subsided I tried it using a match with much better results.
The Reactor’s pot is supplied with a fold-out handle which is very sturdy and positive to grip. It didn’t get hot during my tests. The handle then becomes a nifty locking mechanism which holds on the Reactor’s lid during transport. The lid itself is a clear plastic construction so you can see your water boil, and it has a silicone rubber handle so you can lift it without any risk of burning. Neat.
The Reactor pot is large enough to take the burner and a small gas canister inside it, to save you a little room when packing. Its size would also suggest that it’s a little easier to use to make a meal than a jetboil, and with double the capacity perhaps more suitable for 2-person cooking. However, I don’t really understand why MSR state (repeatedly) on the packaging that it’s a 1.7L pot, and then have a max fill line of 1L. That seems a little misleading to me, or maybe it’s just a legal requirement.
SUMMARY: MSR’s Reactor Stove is very, very quick to boil up water. It knocks the competition in to the shade. But, it has a very low max-fill line for its size, and it’s quite heavy thanks to a very sturdy pot. Brilliantly built and easy to use, it would be good for lightweight treks where you were sharing a load, or even couple camping where you weren’t planning on making complex meals. The inability to use other pans could be a problem for some people.