Stove Fuels

[Martyn]

Just did an interesting experiment.

I boiled a measured 350mls of water on an optimus crux using an optimus terra pot with heat exchanger and it took 5g of green optumus gas (butane/isobutane/propane mix) to bring it to a rolling boil.

I then repeated the test with the same amount of water and the same gas but using a jetboil. This time it only used 4g of gas. The difference might have been less or more than one gram, but my postal scales wont measure less than that. It's interesting though and confirms that the jetboil is a more efficient burner/pot combination.

Anyway, I now know that with one full 100g cannister of optimus gas, an optimus crux and a terra weekend pot, I can boil around 7 litres of water depending on conditions.

Now to do the same test with an alcohol stove (a titanium evernew). If it's just down to fuel, then in theory, with meths having half the calorific value of gas, it should take 10g to boil 350mls. If it takes more fuel than that, then the meths stove is less efficient in comparison to the crux, if it takes less than 10g, then the evernew is comparatively more efficient than the crux. My money is on it being less efficient but we'll see.

I'll let you know.

 

[johnboy]

It'll be interesting to see your results...I assume you'll use the terra nova pot on the TI alcohol burner?? Also to be fair the water temp at start needs to be the same..Have fun....

 

[Martyn]

OK result, I used an evernew alcohol stove, with the matching titanium trivet, standard B&Q meths and the same terra weekend pot I used with the crux. I filled the stove and weighed it. Then lit it, put the trivet on, waited for it to bloom and put the pot on. As soon as the water hit a rolling boil (which incidentally, was one of the quickest boils I've ever seen from this stove), I removed the pot, removed the trivet and snuffed the stove using the snuffer from a classic trangia. Then (using an oven glove to handle the hot stove) I weighed it and it had used 19g of fuel.

That means that this stove and pot combination, is roughly half as efficient as the gas stove tested. Or in practical terms, in order to boil 7 litres, I would need 380 grams or 482mls of meths.

 

[johnboy]

How long between lighting and blooming?? Also when it was burning was the flame incandescent and was there any soot on the base of the terra pot??CheersJohn

 

[Martyn]

How long between lighting and blooming?? Also when it was burning was the flame incandescent and was there any soot on the base of the terra pot??CheersJohn

I didnt time it John, I didnt see the time as being particularly relevant as i was only looking to establish efficiency. I'd say it took about the same length of time to bloom as a trangia. But the stove is a hot burner, that double row of jets makes a difference and the Ti trivet gets red hot and generates a heat feeback into the stove which partially pressurises it. I didnt see any yellow in the flame at all and there was no perceptible sooting. I think the big difference though, was using the terra weekend pot with the fins on the bottom. I really like this combination, I've not tried it before but it was blimmin quick. The downside is that not all the meths was used up and it's a PITA to get unused meths out of the stove. You've pretty much got to experiment with fuel quantities and add exactly what you need and let the stove burn dry. That's always going to mean wastage.

Bottom line, 19g is pretty much what I expected (and that is only fuel burned, not fuel wasted). It pretty much means the stove has half the efficiency of a gas stove as well as the fuel having half the calories. So you need 4x more (in weight) meths to get the same amount of hot water, than you would need gas, paraffin or petrol. It pretty much nails the coffin lid in terms of meths being the ultralight option for me. Sounds obvious, but it's only lighter, if the amount of fuel you need, plus stove, pot stand, fuel bottle and wind shield comes in at under 280g (or in your case with your Ti stove, 240g). Otherwise you get tons more bang for your buck out of gas, paraffin or petrol - but particularly gas.

 

[johnboy]

Drop me a pm I can send you one of those TI gassies for a play..CheersJohn

 

[Martyn]

Drop me a pm I can send you one of those TI gassies for a play..CheersJohn

Nice one, will do mate.

Tomorrow, I think I'll do this test again, but with a SVEA123 and an Optimus Nova.

 

[gliderrider]

This is getting WAY too technical for me, but thanks for the help none the less.

I'm not planning on doing any marathon un supported events, so I think I'll stick to the Jetboil with a 200g cartridge, rather than digging the Trangia out of the loft, or getting a fancy multi fuel MSR stove pump joby.(well, it will still be on the christmas list though, you never know)

 

[Martyn]

Just tested the SVEA123 and it used 6g of Coleman fuel. I should say that I used a mini-pump to pressurise the stove a little, then bled out a small amount of petrol to prime, rather than using meths. I think this is the most fuel efficient priming method as it doesnt require meths or paste to prime and the stove is already pressurised and almost ready to run, but you do have to factor the small amount of additional weight for the mini-pump (42g). To be honest, I was surprised by this, I thought it would use more, especially as I was using the stoves own fuel to prime. There was some incandescence as the stove warmed up and a little pulsing too, but I put the terra pot on as soon as I could and ignored the pulsing in an effort to use the least fuel possible for the test. There was some light sooting to the pot.

Now for the optimus nova.

 

[Martyn]

Right, the Optimus Nova used 11g of Coleman fuel, making it a much less efficient option [for simply brewing up] than the SVEA, but I think this is not a reflection of the burner itself, but the priming and shutdown process of the nova. It takes longer to prime than the SVEA and more fuel needs to be bled into the priming pan. It also burns hotter at 10,000 BTU compared to the 4500BTU of the SVEA. Also shutdown involves inverting the fuel bottle into the off position and allowing the pressure and fuel in the lines to bleed out. All of this means more fuel used - in fact I'd hazard a guess that 50% of the fuel used in this test, was during prime and shutdown. It takes almost 60 seconds for the fuel to bleed out after inverting the bottle and it doesnt take much more than that to actually boil the water. I could have simply turned the stove off and weighed it, but this is not a fair reflection of how the stove would be used in practice. It might be that when cooking a stew for 30 minutes, or melting snow that the fuel hungry prime and shutdown procedures even out and the stove becomes more efficient. But for the purposes of simply bringing 350mls of water to the boil, fantastic stove as the Nova is, it is clearly not the most efficient option. One possible getaround, would be to invert the fuel bottle before the water has come to the boil. If you judge it well, then the fuel bleeding out of the line should be enough to finish off the boil. Bit of trial and error required on that but worth thinking about if you are trying to conserve calories.

One last test, the classic trangia.

 

[ged]

Just tested the SVEA123 and it used 6g of Coleman fuel. ... I was surprised ...

If the 123 has a drawback it's the small tank, but for a quick brew it's excellent. I find that if I pour a bit of meths over the tank and then set light to it to warm it up, it speeds up the burner preheat and it doesn't need a pump. Although it does nothing for burner preheat I use the same technique on the wife's 8R but please don't tell her I said that.

For fuel efficiency I've been very pleasantly surprised by the old 96 that I picked up on Chesterfield market. When I tested it soon after I got it, it only used 6g of paraffin to boil half a litre of water in an ordinary Trangia aluminium kettle. A bit of a faff to assemble it and then get it burning well though.

 

[rik_uk3]

If the 123 has a drawback it's the small tank, but for a quick brew it's excellent. I find that if I pour a bit of meths over the tank and then set light to it to warm it up, it speeds up the burner preheat and it doesn't need a pump. Although it does nothing for burner preheat I use the same technique on the wife's 8R but please don't tell her I said that.

For fuel efficiency I've been very pleasantly surprised by the old 96 that I picked up on Chesterfield market. When I tested it soon after I got it, it only used 6g of paraffin to boil half a litre of water in an ordinary Trangia aluminium kettle. A bit of a faff to assemble it and then get it burning well though.

Same here Ged, bit of fuel in the bottom of an 8 and you can leave the pump at home even in winter. These days with the 123's, 8', 71's and No7's I wrap a bit of fibre glass cloth around the base of the burner which wicks up that bit of extra fuel so you can again leave the pump.

I used to do a lot of stove testing when I was new to stoves but stopped. The problem is there are so many variables in these experiments that at best the results only give you a good indication of performance. There is a guy on youtube (mate of Rob aka RJBurg for the stovies here) that tests a lot of alcohol burners. He uses the same pan in each test IIRC and lets the stoves bloom before putting on the water; he starts timing when the water hits 60f which seems a good system.

Martyn's results don't supprise me but obviously you'd not rely on cooking big meals on an 8 but for one or two folk they are great stoves. Re: Nova, I took one on my last five day trip with 900mls of paraffin and it cooked four full breakfasts and four big 'one pot' meals for four and I came home with fuel. It boils fast but simmers very very well hence its pretty frugal on fuel, general opinion is its better with paraffin than naptha.

Love the 96's Ged but have a Radius 121 set up for brew duty, its a cracker. Fill cup with meths, light, close valve and it primes and lights, no pumping require other than to get up to full blast

 

[Martyn]

Just done the same test on the classic trangia, using the same Ti trivet and terra pot and that used 18g of meths. That makes it a fraction more efficient than the evernew, but significantly, there is nil wastage with the classic trangia as you can screw a lid onto the stove to conserve the meths. However, it did take nearly twice as long to boil - I didnt time it so it could be my imagination, but it seemed to take ages compared to the evernew and obviously the stove itself weighs 3x as much. But in terms of efficiency, it beats the evernew by a whisker.

 

[Martyn]

Martyn's results don't supprise me but obviously you'd not rely on cooking big meals on an 8 but for one or two folk they are great stoves. Re: Nova, I took one on my last five day trip with 900mls of paraffin and it cooked four full breakfasts and four big 'one pot' meals for four and I came home with fuel. It boils fast but simmers very very well hence its pretty frugal on fuel, general opinion is its better with paraffin than naptha.

That's my experience too. We used a Nova quite a bit in the lakes a couple of weeks ago. We used it to warn up a dutch oven full of stew, cook breakasts for 6 and cook a Lancashire hotpot. This is where the stove excels and the few g of extra fuel used in the prime and shutdown are irrelevant. It's a fantastic stove and one of my favourites, but it's come out as one of the least efficient for simply making a cup of tea. It works best when it's hot and the 90 seconds it takes to boil 350mls of water, doesnt let it get into it's stride. That said, if all you are about is making tea and boil in the bag at sea level in fair weather, then at least these tests suggest there are better stove options for that role.

 

[rik_uk3]

"That said, if all you are about is making tea and boil in the bag at sea level in fair weather, then at least these tests suggest there are better stove options for that role."

I'd take one of my old Camping Gaz Bluets for that For just brews and BITB and Jetboil/ETA Exress/Chinese clone/heat exchanger pots will fit the bill. That said my Omnifuel runs like a rocket whatever fuel so leave the pump at home and take a can of gas; at least you can invert the gas can in cold weather, you can't do that with a Jetboil or ETA Express.

 

[Martyn]

Just to summarise the results....

Optimus crux: 5g (optimus gas)
Jetboil: 4g (optimus gas)
Evernew alcohol stove: 19g (B&Q meths)
SVEA 123: 6g (coleman fuel)
Optimus Nova: 11g (coleman fuel)
Classic Trangia: 18g (B&Q meths)

This allows us to create a rank in order of efficiency. Bear in mind this is based on boiling 350 mls of cold water in a cold pot (tera weekend) with a cold stove and include any fuel used in warm up and prime. It's done at a little above sea level and in mild ambient temperatures, all done under cover. This order almost certainly would change with longer cooking times, altitude, bad weather, different cooking pot and an almost endless list of other variables, but it gives a fair baseline for simple "brewing up" conditions. Gas and petrol/paraffin can be compared directly as both fuel types have about the same calorific value. Methanol though, has half the calorific value, so the way to determine efficiency with this fuel type in comparison to stoves which use more calorific fuels, is to simply halve the values for the meths stoves. The jetboil was the most efficient, so we will give that a value of 1 in order to compare the other stoves.

This gives us a rank of...

1. Jetboil: 1.00 (4/4)
2. Optimus Crux: 0.80 (4/5)
3. SVEA123: 0.66 (4/6)
4. Classic Trangia 0.44 (4/(18/2)) *adjusted for the lower calorific value of meths.
5. Evernew 0.42 (4/(19/2)) *adjusted for the lower calorific value of meths.
6. Optimus Nova 0.36 (4/11)

This rank should give you an idea of how much extra fuel (over a jetboil) you need to carry for a given stove, based on efficiency. Remember to x2 for the meths stoves though.

For example, an Optimus Nova is 36% as efficient as a jetboil, so you will need to carry roughly 3x more fuel [in grams] to boil the same amount of water (in batches of 350mls). This was a bit of a revelation really, because the nova is one of my favourite stoves. But the bottom line is that when used for quick boils, it's a wasteful stove compared to the others. I suspect that if the test were repeated for large group cooking, melting snow, simmering stew for hours etc, then the nova would jump up that table to a much higher position. But this test was just for simple boiling of a mug of water and this is how the numbers run. They are what they are and much as I would like the nova to do better in this regard, it didn't.

The obvious winners are the gas stoves, which convert far more of the available calories in the fuel, into heat in the water. This is probably enhanced by the fact that you dont need to prime them. A surprise was the SVEA, what a frugal little stove that is. I suspect the opposite of the nova, if used for large group cooking, melting snow etc, it may drop down the table to a lower position, but for quick boils, it's quite a good option - though the intrinsic weight of the stove makes is questionable compared to gas and it is only 66% the efficiency of a jetboil, which means you'd need to carry 33% more fuel to boil the same amount of water, but a good option if you are our for weeks at a time. It fits the role of a mountaineering stove well, which is no surprise. Meths - well the stoves do OK when the numbers are artificially adjusted for the lack of calories in the fuel, but you cant get past that. They are always going to be bringing up the rear. The only time that meths is the lightest option, is if the gross weight of all your meths gear, comes in under 280 grams. Otherwise, gas knocks it into a coked hat. There are other factors, but if weight is your major consideration, then meths wins for 1 or 2 nights, after that gas gives you much more mileage and really continues to do so until you are into carrying a large bulk of fuel, when several big, comparatively light bottles of petrol makes more sense than two dozen gas cannisters.

 

[gliderrider]

Thank you guys, and martyn, your my hero.

 

[rik_uk3]

Still too many variables Martyn, pot used, water temp, wind (vitally important). The 123 has half the BTU output of a Nova so which would boil first using a wide based pan? (FYI, the Nova has a high standing flame minus pot but goes to very widespead with a pot on so it benefits from a pan at least six inches wide). Take a standard Optimus 111 roarer paraffin and a 111T multifuel burning paraffin, about the same output but the 111T is extremely susceptible to any wind so who would win the boil race.

Interesting and fun post though thanks for taking the time.

 

[Martyn]

Still too many variables Martyn, pot used, water temp, wind (vitally important). The 123 has half the BTU output of a Nova so which would boil first using a wide based pan? (FYI, the Nova has a high standing flame minus pot but goes to very widespead with a pot on so it benefits from a pan at least six inches wide). Take a standard Optimus 111 roarer paraffin and a 111T multifuel burning paraffin, about the same output but the 111T is extremely susceptible to any wind so who would win the boil race.

Interesting and fun post though thanks for taking the time.

It's not about speed, it's about how much fuel is used Rik. Which stove boils first, is irrelevant. We are debating efficiency, not effectiveness. The pot used was a wide based terra weekend with heat exchanger fins on the base. It's about as efficient as you can get, regardless of the burner used under it. The prime and bleed out of the nova is not affected by pot diameter or wind direction. I didnt test the 111, so that is irrelevant, but if you feel your stove is affected adversly by wind, then use a windshield.

But thanks for your comments, they always make me smile.

 

[ateallthepies]

Does anyone know the weight of 30mL/1 oz of Meths please in grams, my scales don't go down that far accurately?

Steve.

Edit... Tried my scales and got 28 grams??