  They do seem to launch a new stove every five months or so don't they!
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 "an inner pot made from hygienic Polypropylene" That sounds rather like one of my CoLab entries of last year (which was just a little tongue-in-cheek...). I've often wondered why so few pan manufacturers don't offer custom PP cookwear (e.g. for cozy cooking), so that was the CoLab entry, along with a custom meths bottle to fit in a pan.
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Presumably, any stove that is 100% efficient will heat your brew up without using any fuel at all.
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> Presumably, any stove that is 100% efficient will heat your brew up without using any fuel at all. Errr... no. Just that the heat transfer between fuel and pan content would be 100% efficient.
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Presumably, any stove that is 100% efficient will heat your brew up without using any fuel at all.
That would be a bit like one of those fabled machines made during the age of steam that "provided" the energy it needed to keep itself going. What were they called? Perpetual motion machines or something like that.
CP - paranoid are you about people stealing your ideas? Just because your paranoid doesn't mean they're not out to steal your ideas. No what was that idea I've just had, oh yes a pan shaped fuelbottle. Of course there already is a most excellent pan shaped fuel container. They put gas in it and the 100g fits neatly into my mug pan and 250g can into my AGG pan (lighter than any Ti mug type pan I've seen). My primus stove fits in with them quite nicely.
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Oh dear! I now have a problem. I really like primus as a brand and intent to get my hands on a primus eta express. Now I really like this one too. My real problem is I bought a trangia mini and then a honey stove. Also I have an AGG cookset with the can type stove. If I get any more stoves I won;t know what to do. As it is I have yet to use the trangia. AGG can stove and the honey stove properly in the hills. Now it looks like I will have the eta express and this new one too. I really don't know what to do. I could get out more into the hills. Or take more than one stove. Now who can I pursuade to carry things. YOu know cooking kit is only lightweight if you only carry one set at a time.
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 Stove efficiency! Aaaah... I have absolutely no idea how Primus define their efficiency measurement, but I'd hope that 100% efficient means that all available energy made it into the pan. I.e 100% efficiency would be the impossible task of transferring 100% of the ideal enthalpy of complete combustion (whatever fuel you had chosen) into the foodstuff in the pan - typically water. Stove efficiency would therefore be the amalgamation of combustion efficiency (how well the flame achieves complete oxidisation of the fuel) and thermal transfer efficiency from the flame to the pan. Obviously, this efficiency is a function of how hot the pan content has already become so changes with time; so we'd have to say maintaining a boil to give a fair test. Basically what I am getting at is that it's nearly impossible to measure this fairly. Probably the best practical measurement is therefore how many litres of water can be brought to the boil from one specific gas cartridge and compare this with the competition...
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 If I get any more stoves I won't know what to do. obviously you need to get more tents, to match them up... (for us, Spacepacker goes with theOD Camp 3 micro stove, small and light, Kaitum goes with the Primus Gravity EF, luxury but still fairly light, Tarra matched to theTrangia with gas conversion, weight not an issue) Pete.
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Nah! Diddy is the tent demon, I'm the stove demon. I still want a bushcooker at some point and an esbit / solid fuel stove. One of those Vargo triad xe dual fuel types. A decagon stove for use with the bushcooker and for durability. A white box stove for efficiency. Maybe one of those stoves made by the guy on this forum to test whether to get the bushbuddy ultra or bushcooker later on. I already have one of those old style thermotech stoves, an old UL coleman (the one that was at the time the lightest and came with piezo ignition and folding arms that were to flexible (fast boil time though). Also another old gas stove that I have somewhere just can;t find. I think I am on about 6 or 7 stoves owned but this will be increased once I have more money saved. Tent-wise I am only on 2, although at £50 I think the Vango Spectre 200 is a no-brainer purchase for solo car camping. Still no-where near Diddy on tents, but getting quite good on stoves. BTW
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BTW Peter which stove with which tent? Tents - JW Pocket Hotel, Force10 Vitesse (single skin) and soon to be Vango Spectre 200 Stoves - Go-gas Thermotech, Primus micron (old name) /express, AGG can type stove, mini trangia, honey stove. I would think the AGG cookset with the can stove for the vitesse or the primus with a titanium mug for a pan, go-gas thermotech for the heavy old pocket hotel and possibly the spectre and finally the mini trangia with the spectre or even the honey stove so I can sit outside in the summer with a real fire or use the meths when not allowed a fire. I will have to get more tents so one stove per tent. I will be getting a tarp which would best be used with the honey stove in wood fire mode to keep the mossies away.
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BTW Peter which stove with which tent? Read it again, they're all in there. Pete.
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Asked for... never mind. Where did all the talk of 100% efficiency come from? its 80% in the blurb double the 40%.
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Time to go.. the point of the 100% is that if you haven't defined what you mean by 100% then you have no idea what is intended by 80% or 40%!
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 In theory... You know how much energy can be released through combustion per g of the gas, and you know how much energy it takes to raise the temperature of water, so its just a case of working out how much gas is used to rase the temperature of X grams of water by X degrees. Havent a clue if thats how they do it, but would make sense to me. This would be done at standard temperature and pressure, and obviously bares no relationship to trying to cook you pot noodle on a windy hillside, while attempting to fighting the sheep off that wants to eat you rucksack.
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If your really bored look through a standards catalogue, you can get all sorts of standards for testing stuff, ranging from standard lager, to standard digestives, to standard piss. My mate used standard piss for checking equipment used in analysing workers wee looking for mercury used in seed dressings. Wonder ifthey used the standard lager to make the standard wee.
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Oh, sorry TTG, brain in "not yet enough coffee mode"... JW Pocket Hotel with Thermotech Force10 Vitesse (single skin) with Micron Maybe the trangia with the Spectre (or the Thermotech?) Think the can and honey would really need you to get a tarp for that back to basics prefab feel... An Eta would call for something Scandanavian, not the lightest in town but arguably the best. I think you know where that's going... Pete.
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I totally agree Jon & it's what I said above - just phrased the other way around (how much water to boiling per bottle of gas as opposed to how much gas to boiling per litre of water). However I don't think this is what the stove people actually measure... but as I can't tell what it is they do measure I find the whole thing a bit pointless. Suffice to say that this Primus stove is more efficient than that Primus stove! That's about all I can be sure of from the marketese! Incidentally, in my line of work, we talk about a measure of ISP in rocketry for the combination of the design of an engine and it's fuel/oxidant behaviour. Generally speaking, the higher the better. And this is why solar sails are considered such a bright (no pun intended) idea. By using light as your propulsion method, you get 'free' power for no additional mass. The parallel in the outdoors cooking world is the solar oven. I doubt that a design could be made practical for the outdoors enthusiast as 1) you can only cook in daylight, 2) you need to capture a good area of bright sunlight so the devices tend to be a bit big and 3) they are weather dependent. But they are an excellent idea for long-term basecamp use, saving fuel cost & weight, especially nearer the tropics where the insolation is high IMO. If we could have one metric for stoves - such as fuel grams to raise a litre of water from 10C to boiling point - then they'd be a lot easier to compare! John
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> Basically what I am getting at is that it's nearly impossible to measure this fairly. Not very hard, really. Assuming you know the composition of your fuel, you can weigh before and after weights of the canister after raising a known volume of water through a delta T. I suspect that they'd use the lower heating value of the fuel, since it's not a condensing stove, so the latent heat of the water of combustion would be lost. I was trying to do this with my meths stoves burners a while back. Ah, yes, here we are... My meths stoves are apparently 53% efficient...
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What prompted my 100% jibe was just that Primus don't explain what they mean by 80% efficient. It struck me as pure marketing hype along the lines of Gore's "guaranteed to keep you dry" claim. It would have been fair enough if they'd said "80% of the heat generated transferred to the contents of the pot", but they didn't.
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CP, what I meant by my comment 'nearly impossible to measure this fairly' is that, in the wide array of available stove/fuel/pot combinations I can't see how a stove on its own could be rated this way. As you have aptly explained on other threads, the heat transfer to your pot of water depends on many factors... shape of the pot; material properties; clearance between the flame front & the base; heat shielding & radiant reflection from below etc. etc. etc. Primus can market their cooking system as 80% efficient if they like; but it doesn't help compare it to any other system unless all components are measured together.
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