Trangia stoves investigated

Introduction

The main features of the stove are a set of nesting pots, a two-piece wind-shield / pot-stand, and a simple, but powerful, methylated spirits (alcohol) burner. The stove is almost silent in operation, and its fuel is a renewable resource produced by fermentation. Metho is cheap (less than $3 per litre) and is widely available at any service station or supermarket. Furthermore, the stove does not require disposable fuel canisters and never needs maintenance.

The only real disadvantages of Trangia's are their weight, and their slowness when compared to pressurized fuel stoves. Due to the weight of the integral wind-shield, many bushwalkers have tried to find ways to replace it with a light-weight pot support. In fact, Trangia itself sells a light-weight version of the stove which does just this (the "28" model). However without a wind shield, the efficiency of the stove is somewhat reduced in cold or windy conditions - meaning that cooking time is longer and more fuel needs to be carried.

1. Stove boil times

But just how slow is the Trangia compared to other camping stoves ? In a recent stove survey, I read that a Trangia took 13 minutes to boil a litre of water - but based on personal experience with my Trangia 25, I didn't believe it was that slow. On the yellow bag that the burner comes in, the manufacturer says that it will boil a litre of water in 10-15 minutes. This seemed like a very conservative estimate on Trangia's part. So I set out to find some figures for myself.

The Trangia burner at full power

The tests below involved boiling a litre of tap water at sea-level, in a sheltered outdoors location on two different nights. Ambient temperature was about 19 deg C the first night and 14 deg C the second night. A Trangia Duossal 25 stove was used. Timing was stopped when a vigourous boil was achieved. All times are +/- 30 sec.

Test 1:

As you can see from the results above, the main factors affecting boil-times are the ambient temperature and the initial temperature of the water. The lowest water temperature tested was zero degrees. This was done by leaving a bottle of water in the freezer until it started to ice over, and then pouring it into the cooking pot. With an air temperature of 13 deg C, the Trangia still managed to boil it in 12 minutes! Of course, I was not able to test the stove with an air temperature of zero at this time of year (October) near Sydney, but that would no doubt increase boil time somewhat too. (UPDATE: Testing in winter confirmed that ambient temp has a significant affect on boil times - increasing them by 2-3 minutes at 8 deg C)

Test 2:

The above results show that the initial state of the stove makes a big difference to the boil times. The longer the stove has been running, the quicker it will boil a litre of water. There are at least two reasons for this.

The first reason is that the burner only achieves maximum power output when the jets begin to operate fully. This takes at least a 1-2 minutes of burner operation and is often accompanied by a "pop" sound.

The second reason is that the stove housing warms up significantly during several minutes of operation. This combination of factors explains why the second litre of water boil test took only 6.5 minutes !

Conclusions:

For further discussion of Trangia burner efficiency, check out this fascinating page that I found on the web...Trangia Alcohol Stoves. The graph showing the effect of distance between burner and pot is interesting. Trangia stoves have the burner placed about 30mm below the pot which is pretty close to optimal.

2. Stove weight

Trangia stoves are known to be somewhat heavier than other modern bushwalking stoves. But exactly how heavy are they, and what can be done to reduce this weight ?

The complete Trangia 25 Duossal (Stainless/Aluminium) stove

A recent Wild magazine survey reported the Trangia Duossal 25 to be 1390 grams. This weight must include the optional kettle, which I do not have. I weighed my own Duossal 25 and got a figure of 1150 grams. To check that my scales were reading true, I placed a 1 kg bag of rice on them and they measured exactly one kilogram (+/- 50g).

Next, I weighed all the components of the stove separately. The results are shown in the table below:

As you can see, the burner weighs only 100g - less than almost all the gas stoves listed in the Wild survey. But of course, you need some way to support a pot above the burner. I have seen a number of construction projects on the internet for building light-weight pot supports for use with Trangia burners. Trangia itself even offers such a device in recognition of the perceived weight problem with the Trangia systems (See the T28 or mini-Trangia).

Next, I weighed a couple of new stove components that I bought recently with a view to decreasing the weight of the stove equipment that I carry. These are shown below:

Finally, I weighed some workable combinations of stove equipment to see what the best compromise might be. Combinations excluding the wind-shield and/or saucepan (lid) will obviously be less fuel efficient, however on short weekend walks, its easier to carry more fuel in (and none out) than to carry a heavy stove all the way.

If you leave the wind-shields at home you'll need to balance the pots on rocks placed either side of the burner. (The author accepts no responsibility for any scalding or spilt food resulting from this advice! :-) If you don't want to balance the pots precariously, see section 4 below which talks about using a light-weight pot-stand. Remember that there's also nothing stopping you cooking with Trangia pots on the hot coals of an open fire either - conditions permitting of course.

In the table below, all combinations include the essential components (i.e burner and pot handle), and the inverted saucepan (when present) is used as a pot lid:

So, the best you can do and still maintain high fuel efficiency is about 20% reduction in stove weight over the full Duossal T25 system. You can most simply do this by doing the obvious thing - leaving the large pot at home.

If you're prepared to throw efficiency to the wind, you can easily get the stove weight down to 550g by leaving the wind-shields and large pot at home. This gives you a 52% reduction in weight. If you even leave the pot lid at home and buy a non-stick pot instead of the heavier duossal, you can get down to 300g, but hope the weather is kind and take lots of fuel!

Another interesting option ("*" in the table) which gives a very quick boil time in calm weather, is to take the top wind-shield only and place the burner on the ground beneath it. It you take spacers or find some small rocks to hold the wind-shield about 27mm off the ground to create an air-gap, it works remarkably well. With an air temp of 14 deg C and 19 deg C water, I've achieved boil in 8.5 minutes with this approach. Interestingly, if you reduce the height of the spacers by just 6mm, the stove takes a minute longer to boil the water. This effect is almost certainly due to the distance of the burner from the pot rather than the size of the air gap.

Of course, if you own a T27 stove (the 1-2 person one) then the wind-shields and pots will all be smaller and lighter than the figures above (the T27 Duossal stove weighs 950g). Material choice also affects weight. Trangia offers pots made from Aluminum (the classic pots), Duossal (composite of stainless and aluminium), Non-stick, or Titanium. For example, Traniga's Aluminum and non-stick pots weigh about 25% less than their Duossal (stainless steel/aluminium) pots.

Conclusions:

3. Burn times and fuel weight

I then weighed 250 ml of metho, and got a result of 175g. So, a litre of metho weighs about 700g. By my calculations (using the above results and the results from section 1), a litre of metho is enough to boil between 20 and 30 litres of water.

So, if you're on an extended bushwalk, how much fuel will you need to carry ? Lets say you're sharing meals with a friend and you cook a meal each night (2 pots of food + a hot drink), and a cup of coffee for breakfast. (NB: A cup is 250 ml). Lets assume that's equivalent to boiling 3 litres of water per day. Lets also assume you can boil a litre of water with 40ml of fuel (My tests showed this amount of fuel will give you enough time to boil a litre of water. Trangia's documentation is more conservative, stating that 50ml is required). The fuel consumption per day will be about 40ml * 3 = 120 ml. So with 1 litre of fuel between 2 people, you should be able to go away on an 8 day trip.

If you're more conservative, lets say you'll need to boil 4 litres of water a day, and you're going to use 50ml to boil each litre. That means you'll consume 200ml of metho a day, and if you have 1 litre of metho you can go away for 5 days.

Interestingly, if you run the burner with the simmer ring always in place the stove is remarkably fuel efficient. We found this out by accident on a trip many years ago when we borrowed a friend's Trangia but we didn't ask him how to use it. We ended up running the stove for many night's meals with the simmer ring on all the time. Sure, it took a long time to cook dinner, but we used only half the fuel our friend recommended we'd need!

Conclusions:

4. A simple, light-weight pot stand for the Trangia

My new "billy-can stand", inspired by the mini-Trangia stand, was quite simple to make. I just cut off the top of the billy so that it was as tall as possible, while still fitting inside my cooking pot. Then, I scribed out 4 semi-circles equally spaced below the top rim and cut them out. This left four sturdy pieces sticking up to support the pot, while still allowing plenty of room for the flame to exit the stand. Next, I punched and drilled 8 holes equally spaced around the base of the billy. This was to allow air into the stand around the burner. All this took about an hour. You can see the full details of this and other designs here.

Over the next few months I made a few refinements. My optimal design was made from a short section of galvanised iron down-pipe. I just drilled a few holes around the bottom and cut some notches out of the top. This design is light, has good fuel efficiency, and gives a nice clean burn. I've used this on multi-day camping trips and find its very simple and good to use. A version of this made from stainless steel which I have called the MethLite is now available to buy.

The light-weight setup

5. Comparison with MSR PocketRocket

The table below shows a price and weight comparison between the MSR PocketRocket and Trangia camping stoves:

NOTE: (*) System weights and costs above are based on a burner and basic cook-set (2 pots and saucepan). MSR's basic cook-set (2 pots, saucepan, and lid) costs about $90, and weighs 665g.

For extended trips where fuel-efficiency is a major factor, stoves such as the MSR PocketRocket will probably be the best choice. The MSR is also significantly lighter, however Trangia does offer light-weight pot stands as an option to its 350g integral wind-shield.

If you use the Trangia burner and pots with a light-weight pot stand, then the primary factor deciding between an MSR and a Trangia is the fuel. MSR fuel (a propane/butane mix) costs 3 times as much as Trangia fuel, but has 70% more heat output for the same weight of fuel. Another factor to consider is availability. Methylated spirits is widely available whereas fuel for specialised camping stoves will usually need to be bought from a camping store. If travelling by aeroplanes you will generally not be allowed to take fuel of any sort, so you'll need to be able to purchase it at your destination. (Incidentally, if you have any metho left over at the end of a trip, just take it to a service station and they'll happily take it for you - its a handy solvent).

The basic Trangia components are cheaper than those of the MSR. For instance, the basic burner is about $24, a burner plus pot-stand is $32, and the light-weight mini-Trangia is a complete cooking system for one and costs just $52, significantly less than the MSR burner alone ($65). Also keep in mind that Trangia comes with a wind shield. If you want one for the MSR you'll have to buy that separately.

Boiling a litre of water on a Trangia stove consumes about 32g of fuel. This means that each litre boiled (from a cold-start) will cost you about 14 cents in fuel. Not having access to an MSR, I was not able to determine this sort of info on that burner. However, info I found on the web suggests that you need about twice as much metho (by weight) as other stove fuels for comparable heat output. This suggests that to boil a litre of water on the MSR, it will cost you about 46 cents.

Conclusions:

6. Pros and cons of metho as a fuel

Advantages of metho

• Very cheap and readily available
• Comes in recyclable plastic containers, not disposable metal canisters
• Is made from fermentation of sugars, so is a renewable resource
• Is environmentally friendly, burning to give only carbon dioxide and water
• Is a liquid, not a gas so its easy to see how much you have left
• Safer than other liquid fuels - no dangerous flare ups
• Will burn at cold temperatures and high altitude - although somewhat slower
• Metho burners are maintenance free since they contain no moving parts and no small jets which can get blocked
• Metho burners are incredibly reliable
• Metho burners are very quiet - almost silent
• Spare metho makes a handy solvent around the house

Disadvantages of metho

• Metho (ethanol) has a lower heat output per weight of fuel than some other fuels. (Ethanol: 30 kJ/g, Butane: 49 kJ/g).
• Takes longer to boil water than some other fuels. (About twice as long as gas)
• May not be available in some countries or states because of alcohol restrictions.
• Can generally only be bought in 1 litre quantities, so if you have to fly to the start of a walk and need to purchase your fuel there, you may have to buy more then you need.

7. Links to related info

• The MethLite light weight stand
• Criteria for evaluating camping stoves
• Info on methylated spirits
• Building a light-weight pot stand for a Trangia