Depends what you mean by "really cold", and if you're using a cold weather mix...
I was quite surprised at an RSGS talk about a high level ski tour across the Karakorum, which I think would rate as "really cold" for most of us, used gas as the fuel of choice. Up until then I'd assumed everyone used pressure stoves for that sort of thing, but if you can get fuel then gas should actually be okay. It's a lot easier getting petrol or diesel on the fringes of nowhere, but once you're right in the middle there's none of that either...
Trevor, there are no natives in that sort of place... It's effectively a desert with no grazing and incredibly difficult access so anything you use has to be carried in, including fuel. Not even any yak-dung to burn!
Have you never heard of the Mongol empire and its fiercely independent nomadic descendants? They lived there for thousands of years Pete, and some small direct descendant nomadic tribespeople still do. Cannot recall what tv documentary it was I saw it all in, might well have been a Micheal Palin or a Benedict Allen adventure travel thing though. Of course no one lives everywhere out there in the vast wilderness, but indeed there are areas which still periodically are traveresed by nomadic herding tribespeople to this very day, I do very strongly believe.
Karakorum; the capital of the Mongol empire, and Karakorum; the mountain range, are entirely separate places about 2500km apart and related only by name.
In terms of temperatures, upright gas stoves give problems once the temperature gets down to about 5C. They are fine on new canisters, but very poor indeed on the last 15% once all the propane has burnt off. It's OK so long as you can burn the liquid gas, in something like an old Epigas Alpine.
you can burn liquid gas in the ETA Power, but not the ETA express. The Eta power would be very good in extreme cold. You would probably have to make a cradle as the upside down canister would be balancing on the control knob.
The EtaExpress is fine in temperatures around and just below freezing. I tested it for TGO last year - here's a quote from the review "over the winter I undertook a much more severe test, leaving the stove and cartridge outside on a frosty night with 500ml in the pan. In the morning it was -4C and there was ice on the water. The stove lit immediately and boiled the water in three and a half minutes".
I've used the EtaPower in temperatures down to -15C and it's excellent. I've just propped the inverted cartridge against a boot or a pot.
Ilkka, you can't attach the kettle to the stove with the EtaExpress and it's not as effective as the Reactor in windy conditions. However it is much lighter and lower in bulk. I'd compare the Reactor to the EtaPower rather than the EtaExpress as both have 1.7 litre pots (the EtaExpress has a 1 litre pot). The Eta Power has an excellent windshield and is very stable. I think the EtaPower is the best of the stove/pot/heat exchanger systems so far.
Do as the local natives do, in such a situation!
